


U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ENTOMOLOGY— BULLETIN No. 62. 

L. O. HOWARD, Entomologist and Chief of Bureau. 



THE SAN JOSE OK CHINESE SCALE. 



BY 



O. L. MARLATT, 

Entomologist and Acting Chief in Absence of Chief. 



Issued December 5, 1906. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE, 

1 9 06. 






Honog^h 




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U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ENTOMOLOGY— BULLETIN No. 62. 

L. 0. HOWARD, Entomologist and Chief of Bureau. 






THE SAN JOSE OR CHINESE SCALE. 



BY 



C. L. MAELATT, 

Entomologist and Acting Chief in Absence of Chief. 



Issued December 5, 1906. 




WASHINGTON: 

GOVERNMENT 1' HINTING OFFICE, 



1906 



Av 






LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 

Bureau of Entomology, 
Washington, D. C. , August 31, 1906. . 
Sir: I have the honor to submit for publication a manuscript enti- 
tled "The San Jose or Chinese Scale," which is a thoro revision of 
the previous publications on this subject issued by the Department, 
namely, Bulletins Nos. 3 and 12, new series, of this office. In spite 
of the large number of articles which have been published concerning 
this insect in experiment station bulletins and in journals and maga- 
zines, there is a distinct need for a comprehensive treatment of this 
most important subject, and this need, I think, has been met in an 
excellent way by Mr. Marlatt in this manuscript. I recommend that 
it be published as Bulletin No. 62 of this Bureau. 
Respectfully, 

L. O. Howard, 
Entomologist and Chief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 



DEC 7 1906 
D. OF D. 



PREFACE, 



Bulletin No. 3 (new series) of this office, giving a full account of the 
San Jose scale, was presented for publication, under the joint author- 
ship of Doctor Howard and the writer, November 29, 1895, and 
included the results of two years of very thoro study of the San Jose 
scale. Two j^ears later Doctor Howard issued, as Bulletin No. 12 (new 
series), a record of the work to the end of 1897, more particularly giv- 
ing an account of the spread of the San Jose scale in the United States 
during the intervening period and the results of remedial work b} r this 
office and the different experiment stations, together with additions to 
the bibliography. It has now been more than ten } T ears since the 
publication of the larger bulletin giving the full life history of this 
scale pest, and it seems advisable to issue a new general publication 
to include in one bulletin the considerable additions which have been 
made to our information on the subject. 

The portion of Bulletin 3 giving the life histoiy of the insect was 
worked out with great minuteness and is reproduced with little change. 
The facts relating to the original home of the insect, as discovered by 
the writer in 1901 in the course of explorations in China and Japan, 
are incorporated in this bulletin, and the distribution of the insect has 
been brought down to date. 

The literature of the last ten }^ears relating to the San Jose scale is 
of enormous volume, probably exceeding that relating to any other 
insect pest. Most of this literature relates, however, to the strictly 
economic phase of the subject — namely, distribution, injui\y to plants, 
and the means of control — together with legal enactments of various 
foreign countries and of the several States of the Union. The listing 
of all the publications on the San Jose scale subsequent to its appear- 
ance in the East in 1893 would make a bulletin of itself and would 
probably serve no very useful purpose, and therefore no bibliography 
is given in this publication. The earlier writings on this insect are, 
however, recorded in Bulletins 3 and 12. 

The early experimental work with remedies given in Bulletin 3 is 
omitted, and no effort has been made to summarize the enormous 
body of reports on work with remedies recorded m the publications 
of different experiment stations in this country. The results of the 
later work with remedies conducted by this Bureau are to be found 

3 



4 PREFACE. 

in the five different editions of Circular 42, relating to the control of 
the San Jose scale, and in the two editions of Circular 52, relating to- 
the lime, sulfur, and salt wash, and also in several articles in the 
miscellaneous bulletins of the Bureau. 

Inasmuch as a good deal of the present bulletin has been rewritten, 
and as most of the added matter is from articles published by the 
writer, at the suggestion of Doctor Howard this publication is issued 
as a new bulletin of the Bureau series and under single authorship. 
Considerable matter, however, from Bulletin 3, notably that relating 
to life history and habits, has been used, as already indicated, with, 
little change; this publication is largely, therefore, a compilation, with 
the aim of bringing the subject down to date and making it complete 
and available as a means of present information on the habits and 
status of this important scale insect pest.. 

The portion on true parasites (pp. 58-62) was kindly prepared by 
Doctor Howard, who has long been the authority on this group of 

parasitic four-winged flies. 

C. L. XL 



CONTENTS. 



Page. 

Introduction 7 

Present status of the problem 8 

Origin of the insect 10 

Explorations in eastern Asia 11 

Explorations in Japan 11 

Explorations in China 13 

Record of the spread of the insect 15 

History in California and the West 15 

History in the East '..... 16 

Principal sources of infestation in the East 17 

Summary, by States and Territories, of distribution and present condition. 18 

The relation of climate to spread 33 

Habits and life history 34 

Nature of the damage 34 

Food plants 36 

Citrus fruits and the San Jose scale 42 

Life history 43 

Descriptions of scale and insect 51 

Systematic position and relationships 54 

Means of distribution 56 

Parasites and other natural enemies 58 

True parasites (by L. O. Howard) 58 

Predaceous insect enemies 62 

Native and introduced enemies of other scale-insects 62 

The Asiatic-ladybird enemy of the San Jose scale 62 

Fungous and other diseases of the San Jose scale 69 

Means of controlling the San Jose scale 72 

Insecticide applications 72 

The lime-sulfur wash 73 

The soap treatment 75 

Kerosene treatment 76 

The oil- water treatment 77 

Petroleum-soap emulsions 78 

Fumigation of nursery stock 79 

Legislation against the San Jose scale . .' 80 

Index 81 

5 



ILLUSTRATIONS. 



Page. 
Plate I. The San Jose scale and its work: Fig. 1. — Peach tree with top killed 
by the scale. Fig. 2. — Peach twig, moderately infested, showing 
male and female scale. Fig. 3. — Peach limb badly infested with 

scale 8 

II. Map of China and Japan, to illustrate geographical position in relation 

to native home and distribution of San Jose scale ,. 12 

III. Fig. 1. — Japanese apple orchard, showing trellis method of training. 

Fig. 2. — Old native pear orchard of Japan, showing method of 
training • 12 

IV. Fig. 1. — Pony fruit cart in which products of the hill country are 

brought into Pekin, China. Fig. 2. — Portion of street devoted to 

sale of fruits in Pekin, China 14 

V. Life zones of the United States 34 

VI. Fig. 1. — Large apple trees with lower limbs killed by the San Jose 
scale, Youngstown, N. Y. Fig. 2. — Apple infested with San Jose 

scale 34 

VII. Pupating larvae of Chilocorus similis on the terminals of twigs in 

Department orchard - 66 

VIII. Cages used in breeding Asiatic ladybird ( Chilocorus similis) 66 

IX. Steam plants for cooking lime-sulfur wash 74 

TEXT FIGURES. 

Fig. 1. Map of the United States, showing localities known to have been 

infested with the San Jose scale up to 1896 19 

2. Aspidiotus perniciosus: appearance of scale on bark 35 

3. Aspidiotus perniciosus: young larva and developing scale 44 

4. Aspidiotus perniciosus: development of male insect 46 

5. Aspidiotus p>erniciosus: adult male 47 

6. Aspidiotus perniciosus: adult female 48 

7. Aspidiotiphagus citrinus 60 

8. Prospalta aurantii 61 

9. Ablerus clisiocampx: female 61 

10. Microweisea (Pentilia) misella: adults, larvte, pupa3 63 

11. Chilocorus similis: oviposition and early larval stages 65 

12. Chilocbrus similis: later larval stages, pupa, adult 66 

6 



THE SAN JOSE OR CHINESE SCALE. 



INTRODUCTION. 

The San Jose scale is now known to be of Chinese origin. Its name 
is derived from its first point of colonization in America, namely, at 
San Jose, Cal., and is, in a sense, undesirable, as giving an unmerited 
notoriety to the district in California which had the misfortune of 
being the accidental place to first harbor it. A more appropriate des- 
ignation is the Chinese scale, but it is improbable that a new name will 
ever be adopted for an insect which has become so thoroly well known 
and exploited under its original designation. 

Probably no other insect has had so much notoriety as has this spe- 
cies, and certainly none has assumed so great an international impor- 
tance, as indicated b} r the vast amount of interstate and foreign 
legislation which has been enacted relative to it. In all the earlier 
publications of this office, beginning with Comstock's original descrip- 
tion and note in the Report of the Department of Agriculture for 1880, 
the very great economic importance and capacity for harm of this 
scale insect has been commented upon and the fact that there is per- 
haps no insect capable of causing greater damage to fruit interests in 
the United States than the San Jose or pernicious scale. 

It is inconspicuous and often for a time passes unnoticed or unrecog- 
nized. Meanwhile its enormous fecundity enables it to overspread the 
trunk, limbs, foliage, and fruit of the tree attacked (Pis. I, VI), so 
that it is only a question of two or three years, unless proper remedial 
steps be taken, before the condition of the plant becomes hopeless or 
its death is brought about, in capacity for harm this species probably 
exceeds any other scale insect known, and it attacks practically all 
deciduous plants, both those grown for fruit and the ornamentals. Its 
economic importance is further increased by the ease with which it is 
distributed over wide districts thru the agency of nursery stock, 
and the difficult} 7 and, as a rule, impossibility of exterminating it where 
once introduced. Its capacity for evil, which was recognized in its 
earlier work on the Pacific coast, was at once even more strikingly 
demonstrated on its first appearance in the East, and before measures 
of control were undertaken it was much more disastrous in peach 
orchards of Maryland, New Jersey, and other eastern and southern 
States than in California and the West. 

7 



8 THE SAN JOSE OR CHINESE SCALE. 

PRESENT STATUS OF THE PROBLEM. 

The estimates given in our early publications of the seriousness of 
this pest have been more than borne out by the experience of the last 
ten years. Since its appearance on the Atlantic seaboard in the early 
nineties it has, in spite of all efforts at control in nurseries and by 
State quarantine, spread well over the eastern and middle United 
States and into Canada, so that there are now very few regions where 
fruit growing is at all important in which it has not gained permanent 
foothold. Maine and a few of the middle western States have not so 
far reported this scale insert, but it is only a question of time when 
it will complete its extension over the entire fruit-growing areas of 
North America within its climatic range. 

Nevertheless the San Jose scale has not been an unmitigated scourge, 
and the active investigations b} r the Bureau of Entomology of the 
United States Department of Agriculture and the entomologists of the 
State experiment stations have demonstrated the practicability of 
several means of control, and particularly of the lime-sulfur wash; so 
that the fears aroused by this scale insect are rapidly subsiding and it 
no longer is considered as an insurmountable obstacle to the growth 
of deciduous fruits. In the case of certain fruits, as, for example', the 
peach, it has been found that the lime-sulfur wash has a very great 
value as a fungicide, and so much so that some growers are recom- 
mending its use whether the San Jose scale be present in the orchard 
or not. Furthermore, the presence of this scale has led to much more 
careful methods on the part of nurserymen and in the planting and 
care of .stock, thus raising the standard and giving the intelligent and 
conscientious, painstaking grower a distinct advantage over his care- 
less neighbor. The results in the East, in other words, are following 
rather closely on the experience in California and elsewhere on the 
Pacific coast, where the San Jose scale, long looked upon as the worst 
menace of the deciduous-fruit interests, is now not necessarily so 
regarded, and the same benefits have come to California fruit growing 
by the use of better methods of planting, pruning, and care. 

This does not mean that the San Jose scale is to be lookt upon as 
a blessing. The benefits of spraying are not always uniform, and are 
less perhaps in the case of the apple than they are with the peach, 
pear, and the smoother barked fruit trees. The necessity of annual 
spraying of the trees is now clearly shown, and this amounts to a 
very large annual cost, partl3 r offset, as already indicated, bjr the fun- 
gicidal value of the standard lime-sulfur application. Nevertheless, 
neither the injuries from the scale nor the cost of treatment have put 
more than a temporary check upon the advance of the fruit industry, 
and great confidence is being exprest b} T the larger commercial growers 
who follow out the remedies with greatest thoroness and in the most 



Bui. 62, Bureau of Entomology U. S. Dept of Agriculture. 



Plate I. 




PRESENT STATUS OF THE PROBLEM, 9 

practical manner, and who consequently get the best results. It is 
now largely a matter of getting- the owners of small orchards to 
follow a regular annual system of spraying their trees. 

The presence of San Jose scale has not only resulted in a consider- 
able increase of information as to remedies and to improvements in 
the methods of culture which directly relate to itself, but it has been 
a stimulus to improved methods and more efficient means of control 
of other common destructive insects, has demonstrated the necessitv 
of watchfulness against the introduction of similar pests from foreign 
sources, and has led to active efforts in the direction of quarantine 
and inspection on the part of practically all of the several States of 
the Union. 

The control of the San Jose scale by parasitic and predaceous ene- 
mies is increasing all the time, but there seems to be no likelihood that 
either such natural enemies as are noAv in this country or those which 
may hereafter be imported will ever do more than merely lessen the 
abundance of the scale. In other words, from past experience and 
from a large acquaintance with other similar scale pests it is extremely 
improbable that even under the most favorable circumstances will such 
natural enemies reduce this scale as much as would one thoro treatment 
with the lime-sulfur wash or other standard remedy. The insect 
enenry of the scale can only exist when it has scale food; hence a nor- 
mal balance is very soon reached in which the scale and natural enemy 
fluctuate in relative abundance. A complete extermination of the 
scale insect or host will rarely if ever be accomplished, and there will 
probably always be enough scale present to cause spotted and unmark- 
etable fruit. This does not mean that such enemies are not going to 
be helpful. The} 7 will decrease the virulence and destructiveness of 
the scale, but to get clean fruit it will probabty be always necessary 
to spray- A very few scale on a tree will cause spotted fruit even 
when they may not be abundant enough to do the tree itself material 
injury. The fact that a large, succulent scale insect like the fluted 
scale of California has been controlled by a ladybird enemy does not 
necessarily allow one to hope for the same result with the San Jose 
scale. The ladybird and other enemies introduced into California to 
control scales similar to the San Jose scale have not succeeded in the 
same measure at all. This statement is made to correct hopes which 
may be aroused by certain popular articles which have recently 
appeared on the subject of parasites. 

In brief, therefore, the San Jose scale must be recognized as a per- 
manent condition to be met in the growth of deciduous fruits. The 
greatest care should always lie taken in the purchase of nursery stock 
to see that it is absolutely free from infestation, and preferably also 
that it carries with it a certificate of fumigation. Orchards should be 
spiked according to well-established methods annually as soon as the 



10 THE SA1ST JOSE OR CHINESE SCALE. 

first sign of infestation is found. Fruit growers and others interested 
have come to accept this conclusion and are facing the San Jose scale 
problem as one to be regularly dealt with, as with other established 
insect enemies of fruits. The range of food plants of this scale is so 
great that local extermination is out of the question, and it is recog- 
nized as useless to destroy orchards or new stock because of slight 
infestation. The San Jose scale will have so soon gained foothold on 
many ornamental and wild plants that such destruction of orchards 
would be of no avail, and new stock would be very quickly reinfested 
from near-by sources. 

ORIGIN OF THE INSECT. 

The San Jose scale was first established in this country in the early 
seventies at San Jose, Cal., in the grounds of Mr. James Lick. 

Following the studies of Professor Comstock of this pest in Cali- 
fornia in 1880, efforts have been made to determine whence the original 
infestation came; in other words, to locate the native home of this 
insect. The importance of discovering the origin of this scale arises 
from the now well-known fact that where an insect is native it is nor- 
mally kept in check and prevented from assuming am T very destructive 
features, or at least maintaining such conditions over a very long time, 
by natural enemies, either parasitic or predaceous insects or fungous 
or other diseases. Mr. Lick, in whose orchard the scale first appeared, 
was a great lover of plants, and imported trees and shrubs for the 
ornamentation of his grounds from foreign countries, and it was very 
naturally inferred that in some of these importations he had intro- 
duced this insect. Before this investigation started, however, Mr. 
Lick had died, and it was impossible to trace his importations. That 
the scale was not European in origin was evident; otherwise it would 
undoubtedly have come to this country long before with the numerous 
importations of stock from Europe. Its original home was therefore 
naturally placed in some eastern countiy. In the course of the inves- 
tigation it was found that the San Jose scale occurred in the Hawaiian 
Islands, in Chile, in Japan, and in Australia/' In the case of the 
Hawaiian Islands it was conclusively shown, however, that it had been 
carried there on stock from California. The evidence relating to Chile 
and Australia was of a similar nature — namely, that it had come to 
those countries comparatively recently on imported stock. Its occur- 
rence in Japan was not discovered until 1897, and the evidence was far 
from being conclusive that it was indigenous in that countiy ; never- 
theless the belief that Japan was the source of this scale came to be 
rather generally accepted. The objections to it were voiced by Doctor 
Howard and the writer in an article read before the Association of 

a See Bui. No. 3, new series, Div. Ent., IT. S. Dept. Agric, pp. 10-12, 1896. 



EXPLORATIONS IIST JAPAN. 11 

Economic Entomologists in 1899, a showing that at best the evidence 
left the question open. That this scale insect probably had its original 
home in China or Japan seemed, however, to be pretty conclusively 
indicated by the process of exclusion of other countries. Mr. 
Koebele's investigations of the Asiatic tropical regions and Australia 
and New Zealand had been fairly thoro, yet without finding it on native 
plants, and, furthermore, it was not known to occur in South Africa. 
The evidence pointing toward Japan and China was further empha- 
sized by the fact that the San Jose scale is, by its relationship and dis- 
tribution, an insect of the temperate regions rather than of the Tropics. 

EXPLORATIONS IN EASTERN ASIA. 

With the hope of settling the disputed point of the origin of the 
San Jose scale, and, if the native home of the species were discovered, 
to stud}^, collect, and import beneficial insects to control this pest in 
America, the writer, in 1901-2, made a trip of exploration in Japan, 
China, and other Eastern countries, lasting over a 3^ear. The accom- 
panying map (PL II) illustrates the regions explored. Six months 
were devoted to a very thoro exploration of the different islands of 
the Japanese Empire, and three months to China, with shorter periods 
in other regions. The explorations in China and Japan are the only 
ones which bear especially on the San Jose scale problem. 

EXPLORATIONS IN JAPAN. 

During the time spent in Japan, from April to September, 1901, 
the writer visited some forty-two provinces, and explored all the prin- 
cipal islands, representing a stretch in latitude the equivalent of from 
northern Maine to Florida. Altogether these explorations enabled 
him to make a pretty correct judgment on the San Jose scale problem 
in Japan. Japan is not especially a horticultural country. Her com- 
paratively enormous population of 46,000,000 compels the growth of 
cereals and other necessities of life wherever possible. Very little 
land, therefore, is devoted to fruit raising, and fruits are considered 
as luxuries. Nevertheless, practically every dwelling house in Japan 
has a little dooryard or kitchen garden in which are single examples 
of cherry, plum, peach, persimmon, and other trees. Furthermore, 
the roadwa} T s and temple grounds and streets are lined with cherry 
and plum trees, planted for bloom and ornament and not for fruit. 
There are orchard districts in Japan of limited extent. In northern 
and central Japan there are a few peach orchards and a few orchards 
of native pears, and in southern Japan small orchards of orange, 
pomelo, walnut, and other fruits. In old Japan the chief deciduous 
fruit is a native pear grown in small patches of from a fraction of an 

«See Bui. No. 20, new series, Div. Ent., U. S. Dept. Agric, pp. 3&-39, 1899. 



12 THE SAN JOSE OR CHINESE SCALE. 

acre to 2 or 3 acres in extent. These are trained low on over- 
head trellises (PI. HI), and at a short distance look like vine3^ards. 
There are several districts where such orchards occur in considerable 
numbers. These orchards are very ancient, many of them having 
trees more than one hundred years old. If the San Jose scale were 
native to Japan it would occur in these pear orchards, the pear being 
one of the favorite food plants of this scale insect. 

In northern Japan, including the island of Hokkaido, and the northern 
end of the main island, Hondo, apple raising has been introduced in 
modern times very much on the lines followed in this country. Prior 
to the opening of Japan to foreign commerce and exploration the 
apple as an edible fruit was unknown in that country. The orchards 
in northern Japan are chiefly, therefore, of American origin and rep- 
resent American varieties. Most of the stock came from California, 
and much of it was undoubtedly infested with San Jose scale when it 
was received. There is, therefore, thruout these northern apple 
orchards a mild infestation with this scale. The Japanese are very 
enthusiastic in their efforts to gain all the benefits of western civiliza- 
tion, and this is shown in horticultural as well as in other fields. The 
three leading nurseries, therefore, of Japan have been very active dur- 
ing the last twenty or thirty years in importing the different varieties 
of pear, peach, and apple from America, and all three of these nursery 
districts have become infested with San Jose scale, evidently from such 
importations from California, where the scale has been widely dis- 
tributed for thirty years. Outside these nurseries, however, in cen- 
tral and southern Japan, the San Jose scale did not occur, except where 
it had been introduced on new stock from the nurseries referred to. 
The old native pear orchards were free from scale, except where 
replants had been made of American varieties, or new native stock, to 
fill in breaks in the orchards. The infestation was very often just 
beginning and immediately surrounded the replants. In all Japan, 
therefore, in the little house gardens and temple grounds where were 
cherry, plum, and other trees suitable for San Jose scale, this insect 
did not occur, except where the evidence was very plain of its recent 
introduction as indicated. Without going into details of the evidence, 
it is sufficient to say that the conditions in Japan are essentially the 
same as in this country. The San Jose scale is a recent comer. It 
was, in fact, not known in Japan prior to the }^ear 1897, when its 
presence there was first determined, but it has now been scattered 
pretty widely by nursery stock, exactly as in this country, and occurs 
under similar conditions; in other words, only where it has been 
recently introduced. The investigation showed very distinctly that 
Japan could not be considered responsible for the San Jose scale. 

The results and conclusions arrived at by the writer were after- 
wards fully confirmed by a very thoro and painstaking explora- 



Bui. 62, Bureau of Entomology, U. ! 



Plate II. 




Bui. 62, Bureau of Entomology, U. S. Dept. of Agnc 











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Bui. 62, Bureau of Entomology, U. S. Dept. of Agriculture 



Plate III 




Fig. 1.— Japanese Apple Orchard, Showing Trellis Method of Training. 
(Author's Illustration.) 




Fig. 2.— Old Native Pear Orchard of Japan, Showing Method of Training. 
iAuthor'S Illustration.) 



EXPLORATIONS IN CHINA. 13 

tion of the entire Japanese Empire conducted by Japanese entomolo- 
gists under the authority of the Imperial Agricultural Experiment 
Station in Japan. The publication giving the results of this investiga- 
tion" is a very interesting and valuable contribution to our knowledge 
of the subject, and is illustrated b} r numerous maps and figures. 

EXPLORATIONS IN CHINA. 

Investigations up to this point, while freeing Japan from the onus 
of giving the San Jose scale to the world, left the problem unsettled 
as to the original home of this insect. China remained as the most 
likely place of origin, and the writer proceeded to China to continue 
his explorations there. While in Japan a good deal of information 
was gained relative to fruit conditions in China, from English, Ger- 
mau, and American residents who were spending the summer months 
in Japan to escape the rather trying climate of China. In brief, it 
may be stated that deciduous fruits are grown from the Shanghai 
region northward, the peach being practically the only fruit grown to 
any extent about Shanghai. The great apple district of China is the 
region lying back of the city of Chifu in the north. This apple- 
growing industry was started many } T ears ago by a missionary, Doctor 
Nevius, and has assumed very considerable proportions and covers a 
good deal of the province of Shantung. Below Shanghai the orange 
and other subtropical fruits replace the deciduous varieties. North 
of Chifu native fruits only are grown, consisting of the native pear 
and peach, and such wild fruits as wild crab apples and an edible haw 
apple. 

A very considerable exploration of the country lying immediatelj' 
back of Shanghai was made in the course of a long house-boat trip. A 
great many peach orchards were examined and a good deal of mis- 
cellaneous fruit and other plants growing about house yards were 
inspected. Nowhere was there any evidence of the San Jose scale, 
nor were scale insects of any sort much to be seen. The climate of 
this region is unfavorable for such insects and they are normally 
killed out by fungous disease. The writer afterwards proceeded by 
boat to Chifu — a five-day ocean trip from Shanghai, and made a con- 
siderable exploration thruout the apple orchards of this region on 
horseback, visiting, among others, the original orchards planted by 
Doctor Nevius. In all these the San Jose scale was found seatteringlv 
present, not, however, doing any -special damage, and probably not 
enough to be noticed, if its possibility for evil was not so well estab- 
lished. The presence of the San Jose scale in this region did not, 
however, have any special significance, since much of the original 

"The San Jose scale in Japan. Imperial Agricultural Experiment Station, Tokyo, 
1904. 



14 THE SAN JOSE OR CHINESE SCALE. 

stock was obtained from California, and doubtless from nurseries 
which were infested with, the scale! 

The journey of exploration was continued northward to Tientsin and 
Pekin. In this region the San Jose scale was found on native plants 
also, including the flowering peach, a tree grown for ornament solely, 
and not for fruit, and notably on the native fruits in the markets in 
these cities. 

The markets of Pekin were of especial interest in this connection. 
Pekin is the center and market for all the region lying to the north 
and west, and the streets (PL IV, fig. 2) devoted to the sale of fruits 
and other products in the Chinese city are one of the great show 
places. The fruit and nut products are brought into Pekin in little 
two-wheeled carts (PL IV, fig. 1), or more generally on camelback, 
great caravans of heavily loaded camels and streams of carts constantly 
entering the city with the products of the outtying provinces. One 
finds, therefore, in the markets of the Chinese citj^ the fruit products 
of all northern China, and can study them at ease. All the district 
lying between Pekin and the great wall, north and west and east, has 
been most careful^ explored and mapped by the foreign military 
authorities. From various individuals emplo} T ed in this minute sur- 
vey a great deal was learned relative to the fruit growing in the dis- 
trict indicated. Much of the fruit found in the markets of Pekin 
comes from the hill region leading up to the mountains separating 
China from Mongolia and Manchuria. These fruits are native apples, 
pears, and peaches, and the little haw apple already mentioned. Great 
quantities of these fruits were examined in the market, with the excep- 
tion of the peach, which was then out of season, and later similar 
examinations were made at Tientsin. A very scanty but general infes- 
tation with San Jose scale was found on the different fruits examined. 
Perhaps one apple in a hundred would have a few of these scales about 
the blossom end and the same proportion was true of the haw apple 
and the native pear. Thruout the region where these fruits are grown 
there has been no introduction of foreign stock. The occurrence of the 
San Jose scale on these two fruits was conclusive evidence that in the 
region whence they came the San Jose scale is native. The scattering 
occurrence of the scale also indicated, as would be anticipated, that 
this pest in its native home is kept in check by natural means. 

The investigations made at Shanghai, and later southward to Hong- 
kong, the Mala}^ Peninsula, and Java, indicated that the San Jose 
scale in eastern Asia can not survive below Shanghai. 

The sp:cial distiit where it is native and thrives is a fairly well 
shut-off region, wb:ch probably accounts for the failure of this insect 
to beco i.ea world pest ages ago. This district is the region leading 
up to the mountains and comprising the northern and northeastern 



Bui. 62, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate IV. 




Fig. 1.— Pony Fruit Cart in which Products of the Hill Country are Brought 
into Pekin, China. (Author's Illustration.) 




Fig. 2.— Portion of Street Devoted to Sale of Fruits in Pekin, China. 
(Author's Illustration.) 

[In foreground, fruit samples; in background, storehouses, also dromedaries employed to bring 
products from remote provinces.] 



HISTORY IN CALIFORNIA AND THE WEST. 15 

frontiers of China proper. Beyond the great wall on the north and 
west lies Mongolia, consisting chiefly of the vast Desert of Gobi. To 
the northeast, and separating the region from Manchuria and Korea, 
is the eastern Gobi Desert. To the south and east lies the great alluvial 
plain, the product of centuries of mud carried down by the Yellow 
River, a region where cereals only are grown. These are all effective 
barriers, and especially so when considered in connection with the 
political conditions of the past. We have, therefore, as the original 
home of this insect a naturally shut-off area from which it could not 
easily escape under the conditions prevailing up to our own times. 

The means by which the San Jose scale came from China to America 
is a matter of interest. As previously stated, it is believed that this 
pest reached California on trees imported by the late James Lick. 
It is the writer's belief that Mr. Lick imported from China, possibly 
thru Doctor Nevius, with whom he was probably in correspondence, the 
flowering Chinese peach, and brought with it the San Jose scale to his 
premises. Undoubtedly this scale insect came to this country in some 
such way on ornamental stock' from China. 

RECORD OF THE SPREAD OF THE INSECT. 

No attempt will be made to trace the details of the later extension 
of the San Jose scale, but the earlier history of this scale in the 
United States is well worthy of record as is also a summary at least of 
the means by which it became so widely and disastrously distributed 
so shortly after its first appearance on the Atlantic side of the 
Continent. 

HISTORY IN CALIFORNIA AND THE WEST. 

The spread of the San Jose scale from the point of original infesta- 
tion in the San Jose Valley was somewhat rapid, its area increasing in 
every direction, but more rapidly toward the north and the west. B} r 
1873 it had become a serious pest in orchards which had direct con- 
nection with that of Mr. Lick, and in 1880, when Professor Comstock 
studied it, he reported that he had never seen any other species so 
abundant and injurious as this was in certain orchards. As reported 
by Mr. Coquillett, it had extended as far west as San Francisco by 
1883, but it had not reached important deciduous-fruit districts in 
southern California three years later. Prior to its reaching the East 
in 1886 or 1887 it had slowly extended its range on the Pacific coast 
and in States west of the Rocky Mountains, including California, 
Oregon, Washington, and Idaho on the north, and Nevada, Arizona, 
and New Mexico on the south. In the early nineties it had penetrated 
into British Columbia. 
8449— No. 62—06 2 



16 THE SAN JOSE OR CHINESE SCALE. 

HISTORY IN THE EAST. 

The general records of the discovery of the insect in the East are 
reproduced, with slight changes, from Bulletin 3. 

The occurrence of the San Jose scale in the East was first discovered 
early in August, 1893, in the grounds of Dr. C. H. Hedges, of Char- 
lottesville, Va. An infested pear had been sent by Doctor Hedges to 
Mr. Gallowaj 7 , chief of the Division of Vegetable Physiology and 
Pathology of the Department of Agriculture, on the supposition that 
it was affected b} 7 a fungous disease. The fruit was submitted to the 
then acting entomologist, Doctor Howard, who immediately recognized 
the injury as due to the San Jose scale, and the startling and deplor- 
able fact was established of the introduction into eastern orchards of 
this worst scourge of deciduous trees of the Pacific Slope, as well as 
the fact that it was evidently able to maintain itself in a supposedly 
less favorable climate. The importance of this discovery was at once 
realized, and two agents of the Bureau, Messrs. Schwarz and Coquil- 
lett, were detailed to make a thoro investigation. In conjunction with 
the State board of agriculture of Virginia and under the supervision 
of Mr. Coquillett a thoro fumigation with Irydrocyanic acid gas was 
given to the infested trees and plants. 

The introduction of the scale was subsequently traced to currant 
bushes purchased from a New Jersey firm. 

In March, 1891, the presence of the scale was determined by Doctor 
Howard, at Riverside, Charles County, Md., in a rather large orchard 
situated on the river front, and including over two thousand peach 
and several hundred apple trees. This orchard was visited b}- the 
writer, who found that many of the trees were infested with the San 
Jose scale, large numbers having already perished. The infested stock 
was again in this instance traced to a New Jersey nursery. This 
orchard, on account of its proximity to Washington and the facilities 
thus afforded for experiment, was used by the Bureau in the testing 
of various washes for this scale. 

During the same month (March, 1891) specimens of the San Jose 
scale were received from De Funiak Springs, Fla., thru the ento- 
mologist of the Florida Experiment Station, Mr. P. H. Rolfs. The 
late Mr. H. G. Hubbard, one of the assistants of the division, visited 
the infested locality and found the scales confined chiefly to peach 
and plum, occurring, however, in small numbers on Kieffer pear, 
pecan, and persimmon. Manj T thousands of trees were found to be 
infested, including nearly every orchard within a radius of 5 or 6 
miles. The source of the infestation in this case was not definitely 
ascertained, but it was evident after examination that some infested 
nursery had sent a shipment of trees, and the indications were that 



PRINCIPAL SOURCES OF INFEST ATION IN THE EAST. 17 

there had been repeated importations, the first indication of injury 
having been noted six years before. 

On receipt of the Florida specimens Doctor Howard concluded that 
as the scales had been found in three such widely separated locali- 
ties, and as the information gained from the owners of two of the 
affected orchards led to the supposition that the original stock had 
been obtained from a large eastern nursery, the probabilities were 
strong that the scale had established itself in many eastern points 
during the preceding five or six years. He therefore immediately pre- 
pared a circular of warning and had nearly 12,000 copies mailed early 
in April to all eastern agricultural newspapers and to very many eastern 
fruit growers. As a result of the issuing of this circular many new 
localities for the scale were ascertained, a widespread interest in the 
subject was aroused, and careful investigations were made in all the 
States to which there was any likelihood that the insect had been 
carried by nursery stock or other means. 

By the end of August, 1891, the scale was known to occur in the 
following localities in the East: In a rather widely extended district 
in Florida, one locality in Virginia, three in Mar3 T land, one in Indiana, 
two in Pennsylvania, many in New Jersey, and one in New York, on 
the east bank of the Hudson River a little below Albany. Very shortly 
afterwards, during the same summer, it was found on Long Island, 
occurring both in orchards and nurseries. Later in the fall the scale 
was found at three new localities in Maryland, and still later specimens 
were received from the extreme southern part of Georgia. In Decem- 
ber Professor Webster reported receiving the scale from a large 
orchard district in southern Ohio, and a little later specimens were 
received from Jefferson County, Ind. The scale w T as found also near 
New Castle, Del., in Januaiy, 1895, and additional localities were dis- 
covered during the following spring and summer of 1895 in some of 
the States mentioned, as also in Alabama, Louisiana, and Massachu- 
setts. In nearly every instance the source of infestation in the East 
was the same, namely, one or the other of two important New Jersey 
nurseries. 

PRINCIPAL SOURCES OF INFESTATION IN THE EAST. 

As stated, nearly all the eastern occurrences of the San Jose scale 
were traced to two large New Jersey nurseries, from which infested 
stock had unwittingly been sent out broadcast for certainly six or seven 
years. The damage thus done to the fruit interests of the East by 
these nurserymen can hardly be estimated, and yet it must be admitted 
that they were, in a measure, blameless, since they were undoubtedly 
entirely unaware of the dangerous character of the scale insect which 
infested their stock. We can hardly avoid the conclusion, however, 



18 THE SAN JOSE OR CHINESE SCALE. 

that they were aware that they were distributing 1 diseased stock, since 
to deny this presupposes that the stock received no examination. If 
the scale was noticed it was doubtless supposed to be one of the com- 
mon eastern species, which, while bad enough, are of little importance 
compared with the San Jose scale. 

The two nurseries responsible for the original eastern introduction 
of the scale became infested in the same way. Either in 1886 or 1887, 
in the endeavor to secure a thoroly curculio-proof plum, both of these 
nurseries introduced from California an improved Japanese variety, 
the Kelsey, obtained from the San Jose district. We have the state- 
ment from the proprietors of one of the nurseries that the plum trees 
in question were secured in the spring of 1887 from San Jose, CaL, 
and were shipped thru the agency of a Missouri nursery company, which 
acted in this instance apparent^ as a mere transmitting agent. The 
trees were unquestionably thoroly infested when received, did not 
thrive, and in both cases most of them were ultimately taken out and 
destroyed. The stock, however, had been multiplied by nursery 
methods, and from the original stock, and that subsequently obtained, 
the scale spread more or less completely thruout both of the nurseries 
in question. Both of these firms, when the nature of the infestation 
was brought to their attention and the seriousness of the damage they 
were doing was made apparent to them, undertook measures to 
exterminate the scale. 

In addition to the two prominent nurseries mentioned, several smaller 
nurseries in the East were found to harbor this scale. Some of these 
had been recentl} 7 infested, but in others the infestation was of long- 
standing. Three nurseries of the latter class were located on Long 
Island, and apparently received their original scales from New Jersey; 
one in Florida, reported by Prof. P. H. Rolfs, and two in Georgia 
apparently received infested stock from eastern sources, and one or 
more each in Louisiana, Mississippi, and Alabama became infested 
with the scale thru pear stock coming from Lewiston, Idaho. In Mas- 
sachusetts there were infested nurseries at Cambridge and Bedford, 
the origin of the scale in these cases being obscure; and a nursery in 
Missouri was under suspicion as having been the agency thru which 
the original infested Japanese plums were transmitted to eastern 
nurseries. Two infested nurseries were known to exist in Maryland 
also. 

SUMMARY, BY STATES AND TERRITORIES, OF DISTRIBUTION 
AND PRESENT CONDITION. 

The detailed facts relating to the first introduction of the San Jose 
scale into. the several States are given in Bulletins 3 and 12, and with 
greater minuteness in the various publications of the experiment sta- 
tions of the several States involved. The distribution has now become 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 



19 



so general in most of the States where the San Jose scale has occurred 
for a number of years that it is impracticable to indicate the different 
points of infestation, and even in the States worst infested many 
orchards are free from the scale; but if an attempt was made to graph- 
ically picture the distribution on a map, the points of infestation 
would be so numerous as to give the appearance of absolutely complete 
infestation. The publications cited may be referred to, therefore, 
for the more detailed and complete records. A mere statement of the 
present general status of the San Jose scale in the several States in 
which it occurs will now be given. This statement is based on replies 
to a circular letter of inquiry sent to State entomologists and experi- 
ment station officers in May of this 3^ear. 



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Fig. 1.— Map of the United States, showing localities known to have been infested with the San Jose 

scale up to 1896. (Original.) 

It is interesting for comparison to reproduce the map (fig. 1) show- 
ing the known distribution at the time of the publication of Bulletin 3 
in 1896, when the scale was reported in only 20 States and in compara- 
tively few localities in each, with the single exception of New Jersey, 
which had been most energetically inspected by Dr. John B. Smith 
and found to be very general ty infested. Bulletin 12 records the scale 
occurring in 33 States and also in the District of Columbia and Canada, 
and in very manj^ new localities in all of the States previously recorded 
as harboring the scale. The number of actual records of the San 
Jose scale now available are many hundredfold what the}^ were at the 
time of the publication of Bulletin 12 at the beginning of the year 
1898. 

There are still a few States in which the San Jose scale does not 
now occur or has not been reported, namely, Colorado, Maine, Miune- 



20 THE SA1ST JOSE OR CHINESE SCALE. 

sota, Nebraska, North and South Dakota, Wisconsin, and Wyoming. 
It probably occurs in sonie of these States, however, altho it has so 
far escaped notice. 

ALABAMA. 

The occurrence of the San Jose scale in Alabama was first indicated 
in April, 1885, by material received from Prof. J. W. Hoffman, of 
the Tuskegee Institute, Tuskegee. As now reported hy Mr. E. S. 
Mackintosh, State horticulturist, the infestation is scattering thruout 
the State, but chiefly along some of the main railroad lines, and most 
of the infested orchards became so before people knew about the 
scale and before the adoption of quarantine measures to prevent its 
introduction and spread. 

ARIZONA. 

The San Jose scale has been present in Arizona in the older orchards 
of the Salt River Valley for more than twentj' years. Director R. H. 
Forbes, of the agricultural experiment station, now reports that this 
scale insect has rather dropt out of sight, probably because of the 
succession of excessively hot dry years from 1899 to 1901, inclusive. 
During this period a large proportion of the deciduous fruit trees, 
including almonds, peaches, pears, apricots, and apples, perished, 
apparently from lack of irrigating water and partly from the effect of 
extremely high temperature and dryness. 

ARKANSAS. 

The presence of the San Jose scale in this State is recorded in Bul- 
letin 12 (1898), on material reported by Professor Stinson. Mr. C. F. 
Adams, the entomologist of the agricultural experiment station, now 
states that the spread of this insect is still not very general; that it 
has been reported from several counties, and that he has seen it in two 
florists' establishments, but has not found it in any of his nursery 
inspection. 

CALIFORNIA. 

The San Jose scale has, of course, long been generally disseminated 
thruout the State. Prof. C. W. Woodworth, entomologist of the 
agricultural experiment station, now reports that it does not occur at 
Berkeley, but probably occurs everywhere else in the State where fruit 
trees are grown, except in isolated plantings in the foothill regions. 
Usually it is not seriously troublesome, tho it may increase rapidly at 
any time and become a pest. The uniform treatment with the lime, 
sulfur, and salt wash keeps it in check, and parasitism is often fairly 
efficient. In some districts, as about San Jose, where it has almost 
disappeared, the result may be due both to parasitism and to some 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 21 

obscure form of disease as well as to the lime-sulfur treatment. In 
southern California it is particularly troublesome in apple orchards. 
The principal variety of apple grown is the White Pearmain, and the 
comparatively rough bark of this variety makes it difficult to get very 
satisfactory results from the lime-sulfur wash. The varieties of apple 
commonly grown in northern California — for example, Newton Pippin 
and Yellow Bellflower — are smooth barked, and better results with the 
wash are gained. Taking the State as a whole, Professor Wood worth 
says that it will be readity found in at least 25 per cent of the or- 
chards, in injurious numbers in probably 10 per cent in am^ one year, 
and that from 25 per cent to 40 per cent of the orchards are sprayed 
with the lime, sulfur, and salt wash every year. 

COLORADO. 

The San Jose scale has apparent^ not j^et obtained foothold in 
Colorado, but it has been sent to us from Colorado on fruit imported 
from California. The probable explanation is that the fruit regions 
of Colorado are above the climatic range of this scale insect. 

CONNECTICUT. 

The San Jose scale is recorded for at least five localities in Bulletin 
12. The increase of this scale in Connecticut has been pretty rapid, 
and Mr. W. E. Britton, State entomologist, expresses the belief that 
there is now no town in the State which is not infested, tho he may 
not have records from quite all of the towns. It is found very gen- 
erally, at an}^ rate, in all of the larger cities, which are thoroly 
infested. Practically all of the larger orchards are infested, tho per- 
haps only slightly. He says that there are many orchards and trees 
which are still exempt, but that there is no general region of the State 
where the scale can not be found. 

DELAWARE. 

Delaware, as recorded in Bulletins 3 and 12, became generally 
infested very early. Mr. Wesley Webb, secretary of the State board 
of agriculture, now informs us that the San Jose" scale occurs in all 
parts of Newcastle County and in approximately one-half of the 
orchards. In Kent County there are many young peach orchards, 
and more than one-half [ loitiaare infested to a greater or less extent. 
a large proportion of them, however, only slightly so. In the western 
half of Sussex County, along the railroad from Farmington to Delmar, 
nearly half of the orchards are somewhat infested, while in the east- 
ern half of the county from Lincoln southward there are but few 
orchards, and these are comparatively free from scale. 



22 THE SAX JOSE OR CHINESE SCALE. 

DISTRICT OF COLUMBIA. 

The occurrence of the San Jose scale in the District is reported in 
Bulletin 12, and it is now pretty generally distributed on fruit trees 
in the city of Washington and its suburbs. 

FLORIDA. 

The occurrence of the San Jose scale in Florida was brought to our 
attention in March, 1894, as recorded in Bulletin 3, and additional 
localities soon followed. Mr. E. W. Berger, assistant entomologist 
of the State experiment station, reports that the present distribution 
is extensive, the scale occurring in some twenty-odd counties, or 
wherever peaches are grown. 

GEORGIA. 

The early records of Georgia infestation beginning in 1891 are 
given in Bulletins 3 and 12. The San Jose scale in 1891 had a pretty 
strong foothold in this State. The recent conditions in Georgia are 
indicated on a map prepared by Mr. Newell and published in the pro- 
ceedings of the Twenty-eighth Annual Meeting of the Georgia State 
Horticultural Society, in 1901. This map indicates very general 
infestation thruout the State, including most of the counties where 
fruit growing is of any importance. Prof. Hugh N. Starnes, in a 
letter transmitting this report, states that the large increase indicated 
on this map does not mean that infestation is still progressing, but 
merely that it has been more definitely located and the present State 
laws looking to the control of this pest are ample in their provisions and 
are being rigorously enforced. Mr. Newell reports in this connection 
that during 1901 out of a total of 218 nurseries inspected, only 9 were 
found infested, and that this is a very considerable reduction from the 
percentage of infestation shown by records of previous 3-ears. 

IDAHO. 

The infestation in this State is directly from western sources and is 
of long standing, at least in the limited area about Lewiston, where 
the oldest Orchards are located. Mr. L. F. Henderson, the entomolo- 
gist of the State experiment station, reports on the present situation 

under date of May 29 as follows: 

ags 
The scale is very prevalent along the lower river bottoms, such as Lewiston on 

Clearwater, Jnliaetta and Kendrick on Potlatch River (a tributary to Clearwater), 

up and down the Snake at Weiser, Payette, Caldwell, ^Xarupa, as far as Glenns Ferry, 

possibly farther. Its eastern limit seems about Mountain Home, as I do not know of 

it at Shoshone. It does [not?] exist on the upper Snake, as Blaekfoot, nor in the 

extreme southeast, as Montpelier. The elevation of this district seems too high for it. 

as it varies from 4,000 to 7,000 feet altitude. The altitude seems also too high about 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 23 

Moscow and Rathdrum, tho this altitude (2,500 feet) is not more than at Weiser and 
Boise. Possibly greater rainfall in these last districts discourages it. At any rate, 
while it has existed at Lewiston for fifteen years, it has not ascended to Genesee, 12 
miles distant, but nearly 1,800 feet higher. 

In many places it is being well controlled in the orchards, where careful and sys- 
tematic spraying with lime-sulfur spray is done. 

ILLINOIS. 

The San Jose scale was located in Illinois in 1896 by Professor 
Forbes, who, at the end of the following year, had found the scale in 
22 colonies in 11 counties, as reported in Bulletin 12 of this Bureau. 
In a recent letter Professor Forbes gives the details of the present 
infestation, which may be briefly summarized as follows: One-half of 
the counties (51 of the 102) of the State are now known to be more or 
less infested, but 43 per cent of the infested orchards are included in 
2 of these counties and 80 per cent in 5 counties, and in 30 of the 
counties listed the average number of infested orchards is but 3^. 
In four of the counties the infestation is found onty in one or more 
towns and not in orchards. It will be seen from this statement that 
while the San Jose scale is pretty widely scattered thruout the State, 
as it is also in adjoining States, it is far from having gained a gen- 
eral foothold save in a few counties, and even in the worst counties 
infestation is not yet general. In no States has inspection and reme- 
dial work been carried out more thoroty than in Illinois, and this 
accounts for the rather favorable conditions, in view of the fact that 
probably nearly all of the infested orchards and districts have been 
located. 

f INDIANA. 

The first case of infestation was brought to our attention in May, 
1894, and subsequent records are indicated in Bulletins 3 and 12. As 
indicated in a map sent by Prof. J. Troop, horticulturist of the State 
experiment station, the scale is now distributed over the entire State, 
occurring, however, in less than half of the counties. It occurs in 
•all the Ohio River counties, and Vanderburg is indicated as the one 
worst infested. 

IOWA. 

Iowa hitherto has been one of the western States supposedly free 
from the San Jose scale. The State entomologist, Mr. II. E. Summers, 
reports that he now knows of but one infested point in the State, con- 
fined to a single orchard in Louisa County. Some other cases of 
introduction of the scale were discovered a few }'ears ago, but were 
treated in such a thoro way that reinspection during the last three 
years has shown no further development of scale. No San Jose scale 
has been found in an}>- nursery in the State. 



24 THE SAN JOSE OR CHINESE SCALE. 

KANSAS. 

Kansas has long belonged to a group of middle western States free 
from the San Jose scale. During the present year, however, this scale 
insect has been sent to us for determination from Dodge City on apple 
twigs, which is the first and only record so far for this State, on the 
authority of Prof. E. A. Popenoe, entomologist of the State experi- 
ment station. A general examination of the orchards of the State has 
been begun, however, and additional records will probably be dis- 
covered. 

KENTUCKY. 

But one record of the San Jose scale was known in Kentucky at the 
time of the publication of Bulletin 12. Professor Garman, State ento- 
mologist, now reports that the scale is still not generally distributed 
in the State, and the credit for this he believes is due to the prompt 
institution of nursery inspection shortly after the San Jose scale came 
into prominence in the East. Within the past four or live years, how- 
ever, he reports an increase in the number of infested localities, par- 
ticularly in northern counties, and is inclined to believe that in some 
cases the stock condemned on the other side of the river is brought 
over and distributed on the Kentucky side. The infestation is con- 
fined to the river counties and some half a dozen interior counties, all 
lying rather above the median line of the State. 

LOUISIANA. 

The early records of infestation in Louisiana are given in detail in 
Bulletin 3, and the scale is supposed to date in this State from about 
1891, as there recorded. The present situation as given Iry Mr. 
Wilmon Newell, the entomologist of the State experiment stations, 
indicates 12 distinct localities of occurrence, ranging from the north- 
ern line of the State to New Orleans. These points are wideh T sepa- 
rated, and the State is comparative^ free from the scale. Mr. Newell 
states that no very thoro inspection of all the orchard sections of 
the State has been made, but that from the work already done he' 
believes that not over 5 per cent of the orchards, at the outside, are 
infested. But one small nursery is known to be infested, and the 
owner of this nursery is not permitted to place his stock on the market. 

MAINE. 

The San Jose scale has never been reported from Maine, and this is 
confirmed in a recent letter from Miss Edith M. Patch, the entomolo- 
gist of the State experiment station. 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 25 
MARYLAND: 

Maryland early became one of the eastern States worst infested by 
the San Jose scale, and one that suffered most, perhaps, from this 
pest. It also received the most energetic early work in efforts at 
extermination and control. The present situation, as indicated by 
Mr. T. B. Symons, State entomologist, shows the San Jose scale to be 
generally distributed over the entire State, with the exception of the 
two extreme western counties, Garrett and Allegan} 7 , the former hav- 
ing the San Jose scale at 2 points and the latter at 15. By the method 
of employing State inspectors in the various counties, 1,500,000 trees 
of various kinds have been inspected each }'ear for the past four years, 
and from the records thus gained 18 per cent of the fruit trees in- 
spected are infested, and 65 per cent of the orchards, and this estimate 
is believed to be moderate. 

MASSACHUSETTS. 

The presence of the San Jose scale was determined in Massachusetts 
as early as April 25, 1895, as recorded in Bulletin 3. Additional rec- 
ords are given in Bulletin 12. Prof. H. T. Fernald, summing up the 
present situation, says that he was forced to give up the effort of 
keeping a complete list of localities known to be infested in 1900, 
finding that the scale was practically everywhere in Massachusetts 
east of the Connecticut River. At the present time it may be found 
in almost every town to the western boundary of the Connecticut 
Valley, sa} r 15 miles west of the river on the average. In Berkshire 
County, which lies west of this, he has no records, but he would not 
be surprised to find it somewhere in that region, particularly along 
the Housatonic Valley. As to percentage of infestation, he says that 
about one-third of the orchards are infested to a greater or less degree, 
and the infested orchards are particularly the more recentl} 7 planted 
ones. In the older orchards infested replants may occasionall} T be 
found. Many of the cases of infestation, however, are of ornamental 
trees and shrubs in house lots. He states that from such places as 
the Arnold Arboretum and the Metropolitan Park system around 
Boston, which have had the scale for nearly fifteen years, it has 
spread in all directions, and that in Massachusetts it is less an orchard 
problem than one of ornamental plants. 

MICHIGAN. 

Michigan was not known to be infested at the time of the publica- 
tion of Bulletin 3, but Professor Barrows, in August, 1897, reported 
11 localities in lo counties, the evidence showing that the scale had 
been present in the State since 1890, The present situation is indi- 
cated on a map prepared b} T the entomologist of the State experiment 



26 THE SAN JOSE OR CHINESE SCALE. 

station, Mr. R. H. Pettit, with the assistance of Professor Taft, and 
shows scattering infestation thruout the southern third of the State, 
the points farthest north in the interior away from the influence of 
Lake Michigan being at 'Ithaca and Otter Lake, which are both rather 
beyond the anticipated range of the scale insect. It is not shown, 
however, that the extreme points in the range are points of permanent 
infestation. 

MINNESOTA. 

The San Jose scale has not been reported from Minnesota. 

MISSISSIPPI. 

Mississippi apparently became infested with the San Jose scale at 
the same time (1891) and from the same material which carried this 
pest to Louisiana. Mr. Glenn W. Herrick, professor of biology, 
Agricultural College, Miss. , now reports the scale from 16 localities in 
15 counties. It is probable, however, that in portions of Mississippi 
and Louisiana the San Jose scale will not become nearly as serious a 
pest as in northern localities, on account of the action of fungous 
diseases. 

MISSOURI. 

The occurrence of the San Jose scale in 16 localities, as reported by 
Professor Stedman, is noted in Bulletin 12. Mr. Stedman now states 
that the San Jose scale has practically overrun the whole of St. Louis 
County, and that there is a bad case of infestation south of Independ- 
ence, another just west of Cape Girardeau, and one near Charleston. 

MONTANA. 

The San Jose scale has never been reported from Montana. Mr.- 
R. A. Cooley, the State entomologist, reports that during his seven 
years in Montana he has been in touch with all parts of the State, and 
feels sure that if the San Jose scale occurred there he would have 
known of it. A few reported cases investigated have turned out to 
be of other species. 

NEBRASKA. 

The San Jose scale has so far not been found in Nebraska, as reported 
b}^ Prof. Lawrence Bruner, "except on fruit, that has been shipped 
in, principally from Colorado." In view of its nonoccurrence in 
Colorado, the fruit referred to must have come from California or 
elsewhere. 

NEW HAMPSHIRE. 

It was early hoped that the San Jose scale would not be able to 
infest much of the fruit regions of New England, but this hope seems 
to be diminishing, and Prof. Clarence M. Weed reports the San Jose 
scale as far north as the White Mountain region in New Hampshire, 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 27 

to an extent that it is seriously destructive. The records of infes- 
tation show the occurrence of this insect in New Hampshire in the 
eastern part of Manchester, in Dover Point, and Intervale, and in 
nurseries at Dover, Epping', and Seabrook; also in trees from these 
nurseries at Rollinsford, Lee, and Durham. Mr. E. D. Sanderson, 
the present entomologist of the State experiment station, adds two 
additional localities, one in Newington and the other at North Dan- 
ville. Mr. Sanderson reports that no orchard inspections have been 
made, and that as practicall} 7 all of the nursery stock comes originally 
from outside of the State, many of the } T ounger orchards are probably 
infested. 

NEW JERSET. x 

New Jersey, responsible for much of the original distribution of 
the San Jose scale in the East, early became generally infested, as 
recorded in Bulletins 3 and 12. Dr. J. JB. Smith, State entomologist, 
reports that this scale now occurs thruout the State and probably in 
90 per cent of the orchards. In a general way, he says, those dis- 
tricts that are longest infested are in a better condition than those 
that have become more recently infested, because growers in the first 
instance have learned how to deal with the insect to the best advantage. 

NEVADA. 

The occurrence of the San Jose scale in Nevada is noted in Bulletin 
12 in gardens in the city of Reno. We have records also from Carson 
City dating from 1903 and 1901. Prof. J. E. Stubbs, director of the 
State experiment station, writes that the insect is fairly under control 
in the State. In 1904*, he says, and prior to that time, its ravages in 
three or four counties were considerable, and farmers complained that 
the}- were losing their fruit on account of it. At the session of the 
legislature held in 1903 a law was past giving authority to the sev- 
eral counties to appoint an inspector of trees, especially fruit trees. 
In Washoe, Ormsby, Humboldt, Elko, and Lincoln counties these 
inspectors are said to have done pretty good work and to have 
checked the scale b}^ spraying; especially was this true in the counties 
of Washoe and Ormsby. 

NEW MEXICO. 

The distribution of the San Jose scale in New Mexico has "probably 
changed very little since the publication of Bulletins 3 and 12, and no 
late records have been received from this Territory. 

NEW YORK. 

The presence of the scale in New York was determined in August, 
1894, and the early records are noted in Bulletins 3 and 12. The 
present condition of this scale insect in New York has been reported to 



28 THE SAN JOSE OR CHINESE SCALE. 

us by Messrs. M. V. Slingerland and E. P. Felt. Mr. Slingerland gives a 
long list of the infested localities received at the Cornell experiment sta- 
tion, and reports that in general Long Island, the Hudson River Valley, 
and Niagara County seem to be the worst-infested sections. Mr. Felt's 
records were made after consultation with Mr. Atwood, of the State 
department of agriculture, who has direct charge of nursery-inspec- 
tion work. The following counties are reported as badly infested, 
either because of the pest being generally distributed thruout the entire 
county or else because of its inflicting considerable damage in cer- 
tain restricted areas: Albany, Cayuga, Chemung, Columbia, Dutchess, 
Erie, Kings, Nassau, Niagara, Ontario, Orleans, Putnam, Queens, 
Rensselaer, Richmond, Rockland, Suffolk, Wayne, Westchester, and 
Yates. It is also known to occur in the following counties: Broome, 
Chautauqua, Delaware, Fulton, Greene, Jefferson, Madison, Monroe, 
New York, Oneida, Orange, Schenectad}^, Schoharie, Schuyler, Sen- 
eca, Steuben, Tompkins, Ulster, and Washington. Mr. Felt reports 
that the scale may be safely said to be present in most sections where 
fruit interests are at all extensive, tho not always generally distributed. 

NORTH CAROLINA. 

The first records of the occurrence of the San Jose scale in North 
Carolina are given in Bulletin 12. Mr. R. S. Woglum, acting 
entomologist of the North Carolina department of agriculture, has 
submitted a map indicating general infestation thruout the State, 
represented by over fifty counties, in which the number of points 
infested range from 1 to 12. These points are definitely known either 
from personal observation or else from the receipt of specimens on 
plants. West of the Blue Ridge Mountains the region is quite free 
from the scale, only four infested localities being known. 

NORTH DAKOTA. 

No San Jose scale. 

OHIO. 

The early conditions in Ohio, as determined by Prof. F. M. Webster, 
are reported in Bulletins 3 and 12. Mr. A. F. Burgess, chief State 
inspector, gives the following summary of the present conditions: 

Counties having no infested orchards ■ 26 

Counties with 1 infested orchard locality. -•- 27 

Counties with 2 infested orchard localities 10 

Counties with 3 infested orchard localities 10 

Counties with more than 3 infested orchard localities or hav- 
ing large infested areas or numerous small outbreaks 15 

The majority of the larger cities of the State are more or less 
infested. 

These points of infestation cover the State pretty generally. 



SUMMARY OF DISTRIBUTION" AND PRESENT CONDITION. 29 
OKLAHOMA. 

The first records of the San Jose scale in Oklahoma were received 
in 1904, on Japan plum from Mulhall. We have since received it, in 
1905, on peach from Stillwater and El Reno. Mr. J. F. Nicholson, 
entomologist of the agricultural experiment station, reports that the 
scale has been found to a limited extent in five places in the Territory, 
namely, Mulhall, Shawnee, El Reno, Wellston, and Chandler. All of 
these cases are trees in city gardens. 

OREGON. 

Mr. A. B. Cordley, referring to present conditions in Oregon, states 
that to enumerate the localities where the San Jose scale is found would 
be practically to include all places where fruit, is grown. He says that 
it occurs in a very large proportion of the orchards in western Oregon, 
from Ashland to Portland, particularly those along the lines of rail- 
roads or in the vicinity of towns, there being scattered orchards back 
toward the foothills which the San Jose scale has not yet reached. It 
occurs also between Portland and Astoria, along the Columbia River; 
is present in the Hood River Valley, in the Walla Walla Valley in the 
vicinity of Milton and Free water, and in the Grande Ronde Valley in 
the vicinhty of Vale and Ontario. There are, however, large areas of 
central and southern Oregon, remote from the railroads, where little 
fruit is grown, that the scale has not yet reached. It is noted, how- 
ever, that the scale does no great injury except in small farm orchards 
or those that are neglected, and that in all the large orchards the lime, 
sulfur, and salt mixture as a winter spray is in general use. 

PENNSYLVANIA. 

The San Jose scale became early established in Pennsj^lvania from 
New Jersey nurseries, bul, the subject of San Jose scale control was not 
taken up as early in this State as in neighboring States, so that the 
conditions at the outset were not well known. Both Prof. H. A. Sur- 
face, economic zoologist of the State, and Mr. George C. Butz, the 
horticulturist of the agricultural experiment station, agree in the state- 
ment that the San Jose scale is now so widespread in Pennsylvania- 
that there is scarcely a county that has not points of infestation. It 
occurs in practically all the important fruit regions of the State, and 
in many private and public grounds, especialh T in the portion of "Penn- 
sylvania lying east of the Allegheiy Mountains. Mr. Butz reports 
that probably 20 per cent of the orchards are more or less infested. 
Professor Surface has, with the assistance of 30 inspectors, taken up 
active warfare against the scale, inspecting orchards and nurseries and 
trees in parks and giving demonstrations in methods of suppressing 
it. He states that he has not found the scale in the three northeastern 



30 THE SAN" JOSE OR CHINESE SCALE. 

counties of the State, nor in some of the counties northwest of the 
center of the State, such as Cameron, Elk, Forest, McKean, and 
Warren. 

RHODE ISLAND. 

No records from Rhode Island had been received up to the time of 
the publication of Bulletin 12, in 1898, but Mr. A. E. Stene, of the 
College of Agriculture and Mechanic Arts, states that the scale has 
now spread over almost the entire State, and nearby every orchard 
where planting has been done in the last ten years is more or less 
infested. There are a few old orchards where no new trees have 
recently been set that are still free from the scale. It is believed that 
four-fifths of the orchards in the State are infested. 

SOUTH CAROLINA. 

But a single record for South Carolina had been received up to 
the time of the publication of Bulletin 12, largely, as there indicated, 
for the reason that there had been no State entomologist, and no 
work of inspection had been done. The records which have come 
to this office from South Carolina now number 10, and represent 7 
different localities distributed miscellaneously over the State. Natu- 
rally, very few of the actual records would come to us, and the indi- 
cations are that the State is pretty generally infested. Mr. C. E. 
Chambliss, the entomologist of the experiment station, now reports 
24 infested localities, all of which had the scale prior to 1900. 

SOUTH DAKOTA. 

No San Jose scale has yet been reported from South Dakota. Mr. 
W. A. Wheeler, the entomologist of the experiment station, states that 
he has inspected nurseries of South Dakota for two years, and has not 
found the San Jose scale in any nursery. It has been introduced with 
stock received by the college from other States, but has always been 
speedily disposed of when received, and so far is not known to infest 
any of the orchards. 

TENNESSEE. 

A single locality was recorded for the San Jose scale in the eastern 
portion of the State in Bulletin 12. Since that time the number of 
records for the San Jose scale which have come to this office for deter- 
mination has increased to 14. These are distributed generally over the 
State, and indicate rather widespread infestation, and naturally very 
much more than is shown by the material which has been sent to the 
Department. 

A recent letter from Mr. G. M. Bentley, assistant entomologist, 
gives the information that no complete survey of the State has been 



SUMMARY OF DISTRIBUTION AND PRESENT CONDITION. 31 

made, but, roughly speaking, 30 per cent of the nurseries are more or 
less infested, and in eastern Tennessee the San Jose scale is very gen- 
erally present; but the section of the State, notably Franklin County, 
where most of the nurseries are located, is free from the pest. The 
extreme western part of the State, in the Memphis section, is also 
pretty badly infested. No general orchard inspection of the State has 
been made. 

TEXAS. 

Eight localities were reported for Texas in Bulletin 12. The scale 
is now fairly widely distributed in the State, the records of this office 
numbering 19, some of these, however, representing the same district. 
The localities cover, generally speaking, the eastern half of the State, 
namely, the nonarid portion where fruit growing is followed to a 
greater or less extent. Prof. A. F. Conradi, the State entomologist, 
has records of the insect's occurrence in Bexar, Brazonia, Calhoun, 
Cherokee, Comal, Comanche, Eastland, Erath, Galveston, Harris, 
Harrison, Hopkins, Hunt, Valverde, Wharton, and Wood counties. 

UTAH. 

No San Jose scale was recorded for Utah in either Bulletin 3 or 12. 
In 1899 it was sent to us for determination from both Ogden and 
Logan. Mr. E. D. Ball, the entomologist of the State experiment 
station, reports that he is unable to give the exact localities of the 
occurrence of this insect, but states that it is pretty widely spread in 
the central section of the State, doing, however, little damage. It 
seems to be controlled by the twice-stabbed ladybird. The commer- 
cial orchards, as a rule, are practically free. A good deal of spraying 
has been done with the standard lime-sulfur wash. 

VERMONT. 

The occurrence of the San Jose scale in Vermont was brought to 
our notice in 1899. Mr. William Stuart, horticulturist of the State 
experiment station, says that it is now known to occur in only two 
localities, namely, Charlotte, Chittenden County, and Orwell, Rutland 
County; in both instances occurring in only one orchard. 

VIRGINIA. 

The details of the early records in Virginia are given in Bulletin 3 and 
in Bulletin 12. A great many new records have been received from 
Virginia and more material has come to this Bureau for determination 
from Virginia than from any other State except Pennsylvania. Mr. 
J. L. Phillips, State entomologist, in reply to our circular letter refers 

8449— No. 62—06 3 



32 THE SAN JOSE OR CHINESE SCALE. 

to his publications, in which it appears that the San Jose scale is 
recorded from 78 counties. Many orchards in all of the counties are 
still free from the scale, but infestation is very general thruout the 
State. 

WASHINGTON. 

The State of Washington was early infested with the San Jose scale 
from California, and at the time of the publication of Bulletin 3, in 
1896, the fruit-growing regions were pretty well dotted with this pest. 
Mr. A. L. Melander, assistant entomologist, submits, a map which is 
about to be published in a bulletin showing the distribution of this 
insect. It indicates the occurrence of the scale in the western settled 
section of the State, where fruit growing is important, following the 
river vallej'S, but with some important scattering districts on the west 
side of the mountains, where it seems to have a precarious foothold. 
It is little dreaded by orchardists, and fruit trees are commonly spra} r ed 
with the lime, sulfur, and salt wash in February, and one treatment 
is reported to be effective for several years. 

WISCONSIN. 

Wisconsin is, on the authorit}^ of Mr. E. P. Sandsten, horticulturist 
of the State experiment station, now free from the San Jose scale. 
The only occurrence of this pest in the State was three years ago, in 
the extreme southern part, and it was here stamped out by the prompt 
adoption of radical measures. 

WYOMING. 

Mr. B. C. Buffum, director of the agricultural experiment station, 
reports that the San Jose scale has not yet appeared in Wyoming. 
There are but few orchards in bearing, and these are believed to be 
free from this pest. 

WEST VIRGINIA. 

The San Jose scale was first noticed in West Virginia in 1896. 
Many examples of the San Jose scale in this State have been sent to 
this office for determination, showing the scale to be very generally 
distributed. 

The recent reports of the West Virginia experiment station, notably 
those for 1903-1 and 1901-5, and later records received from the 
entomologist of the experiment station, Mr. W. E. Rumsey, indicate 
very general infestation thruout the State, conditions being similar 
to those in Virginia. Nevertheless, while there are hundreds of 
infested orchards and several infested nurseries, the great mass of the 
orchards and nurseries are still free from scale. A very careful 
nursery and orchard inspection is maintained in West Virginia, and 



THE RELATION OF CLIMATE TO SPREAD. 33 

the actual conditions of infestation are perhaps as well known in this 
State as in any other. In many localities the scale is held in check b\ T 
this careful system of inspection and by the prompt and thoro 
adoption of the remedial treatment. * 

CANADA. 

On the authority of Dr. James Fletcher, the Dominion entomolo- 
gist, the San Jose scale infestation in the eastern portion of Canada is 
confined to the Niagara Peninsula and counties along the north shore 
of the west end of Lake Erie. It has also been found in several locali- 
ties in British Columbia, having reached this province in its northward 
migration along the Pacific slope. 

THE RELATION OF CLIMATE TO SPREAD. 

This subject was rather carefully considered in both Bulletins 3 and 
12, in connection with the climatic districts or life zones established 
by Dr. C. Hart Merriam, within which particular animals thrive 
and outside of which they fail to establish themselves. These 
life zones as thus limited have a special value in indicating the 
probable spread of many injurious insects, and seem to be par- 
ticularly significant in the case of the San Jose scale. These life zones 
are: The tropical, occupying small areas in Florida and southern Texas; 
the lower and upper austral, covering the bulk of the United States; 
and the transition zone, coming between the last and the boreal zone 
of Canada northward. These zones will be better understood by refer- 
ence to the accompanying map (PL V). The early records led to the 
belief that the San Jose scale would be practically limited to the upper 
and lower austral zones, and that the important fruit districts in the 
northern United States and in elevated mountain regions, represented 
b} T the transition zone, would be slightly if any infested. In the main, 
the records of the distribution of the San Jose scale have confirmed 
this belief. Nevertheless, the scale has, in a number of instances, 
appeared well into the transition zone as fixt by Doctor Merriam, 
notably in Massachusetts, in New York, in Michigan, and a few other 
points; but in most of these cases the evidence gained from the rela- 
tion of other animals and plants would indicate that the transition and 
upper austral zones were not correctly charted, so that in general the 
belief in the immunity of the transition zone holds. 

As pointed out by Doctor Howard in Bulletin 12. the coastal law 
which brings about the intermingling of northern and southern forms 
will probably justify the eastern Massachusetts occurrences. Other 
occurrences in Massachusetts are justified by the river-valley law in 
relation to the Connecticut River, and Doctor Merriam admits that his 
line across the southern peninsula of Michigan is not very accurately 



34 THE SAN JOSE OR CHINESE SCALE. 

drawn. Special topographical conditions and protecting- mountains 
will probably account for other divergences. 

In the lower austral aud tropical regions the San Jose scale, as 
pointed out by Doctor Howard, may not proye as injurious as in the 
upper austral, and this follows the general rule regarding armored 
scale insects in warm countries. Armored scales rarely appear or 
thrive in the moist Tropics, as shown by the explorations of the writer 
in the East and West Indies. Fungous diseases, which thrive in warm 
and moist climates, are the principal agency in keeping such scale 
insects in check, and in the case of the San Jose scale the common 
scale fungus Sphserostilbe coccophila; has alread}^ done good work in 
Florida and other portions of the lower austral zone. Moisture is a 
prerequisite in the case of this disease, and little benefit comes from 
it in the drier portions of this zone. Too much stress-, however, should 
not be put on zonal limitations, and there may always be outbreaks 
of longer or shorter standing in the borders of the transition region. 

HABITS AND LIFE HISTORY. 
NATURE OF THE DAMAGE. 

The San Jose scale, as already stated, occurs on all parts of the 
plant— limbs (PI. I; PL VI, fig. 1), leaves, and fruit (PL VI, fig. 2). 
As the plant becomes badly infested the scales lie very close together 
on the limbs, frequently overlapping, sometimes with several young 
ones clustering over the surface of an old mature scale. The gen- 
eral appearance which they present is of a grayish, very slightly 
roughened, scurfy deposit. The natural rich reddish color of the 
young limbs of peach, pear, and apple is quite obscured when these 
trees are thickly infested, and they have then every appearance of 
being coated with ashes. When the scales are crusht by scraping, 
a yellowish, oily liquid will appear, resulting from the mashing of 
the soft, yellow insects beneath the scales. Examined under a hand 
lens during the summer, numbers of the little orange-colored larvse 
will be seen running about, and the snowy white young scales will be 
interspersed with the old brown or blackened mature scales. The 
appearance presented at this time under the lens is shown in fig. 2. 
Very frequently the scale has a marked tendency to infest the extrem- 
ities of the branches and twigs. This is particularly noticeable with 
pear. As usually found on peach, the scale is massed often more 
densely on the older growth, and works out more slowly toward the 
new wood. 

The leaves are much less apt to bear scales, but in severe cases the 
upper surface particularly becomes infested, the scales frequently rang- 
ing in two or more quite regular rows on either side of the midrib. 




Corrected to Decembe 



Bul.6£, Bureau of Entomology, U. S. Dept. of Agriculture. 




Bui. 62, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate VI. 



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BBL jSJ^^s 


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is 


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Fig. 1.— Large Apple Trees with Lower Limbs Killed by the San Jose Scale, 
Youngstown, N. Y. i Original. > 




Fig. 2.— Apple Infested with San Jose Scale. Slightly Enlarged (Original 1 . 



NATUKE OF THE DAMAGE. 



35 



The male scales are more numerous on the leaves than the females. 

The infested leaves turn purplish brown. 

The San Jose scale was formerly supposed to differ from all others 

in the peculiar reddening effect which it produces upon the skin of the 

fruit and of tender twigs. This, however, sometimes occurs with other 
?ales, but is a particular^ characteristic feature of this insect, and 
?nders it easy to distinguish. The encircling band of reddish' dis- 
oloration around the margin of each female scale is very noticeable 




CL 

Fig. 2. — Appearance of San Jose scale (Aspidiotus perniciosus) on 
bark: a, infested twig, natural size; b, bark as it a]. pears under 
hand lens, showing scales in various stages of development and 

ytmn.tr larva-, i From Howard and Marlatt.) 

on fruit, especially pears. This appearance, however, sometimes so 
closely resembles the small spots on fruit produced by a common fungus. 
Entomoeporium macidatum Lev., as to require close examination with 
a lens to distinguish it. Fruit severely attacked becomes distorted, 
rough, and pitted, frequently cracking, and may eventually fall prema- 
turely or at least become unmarketable. 

The cambium layer of young twigs where the scales are massed 
together is usually stained deep red or purplish, and when the scale is 
only scattering!}- present the distinctive purplish ring surrounding each 



36 THE SA]ST JOSE OR CHINESE SCALE. 

is almost as noticeable on young twigs as on fruit, and is of the greatest 
service in facilitating the inspection of trees which have been subject 
to possible contagion. The almost microscopic young scale might easily 
elude the most careful search, but the striking circling ring makes it 
a comparatively conspicuous object without the aid of a glass. 

If the tree survives the attack the infested wood eventually becomes 
knotty and irregular, partly from the sapping of the juices by the insect 
and also without doubt largely from the poisoning of the sap of the 
cambium layer by the punctures of the insect, as indicated b} T the dis- 
coloration. Young peach trees will ordinarily survive the scale only 
two or three years. Pears are sometimes killed outright, but generally 
maintain a feeble, sickly existence, making little or no growth for a 
somewhat longer period. 

FOOD PLANTS. 

The San Jose scale may attack almost any deciduous plant, including 
fruits, ornamentals, and the various shade trees. Food-plant lists 
were published in Bulletins 3 and 12 of this Bureau, and several sub- 
sequent writers have given lists, with important additions. The most 
careful investigation of the subject, relating particularly to ornamental 
trees and shrubs, but also to fruit trees, as these are often planted for 
ornament, was that conducted by the State entomologist of Connecti- 
cut, Mr. W. E. Britton, who sent out a circular letter to the entomol- 
ogists and horticultural inspectors of the various States asking for 
data under three headings, namely: (1) Plants commonly infested; 
(2) those occasionally or rarely infested; (3) those not infested. 
Forty -five replies were received, and from these and other records his 
list was prepared. This list I have reproduced, together with his 
following explanatory paragraphs. a 

List of Hardy Trees, Shrubs, and Vines. 

commonly or badly infested. 

Acacia sp. Lintner, Felt, N. Y. ; Alwood, Va. 

Akebia sp. Felt, N. Y. 

Akebia quinata Decaisne. Alwood, Ya. 

AmelancMer canadensis Medic., and other species. Shad-bush, Jvmeberry. Britton, 

Koehler, Conn.; Alwood, Ya. 
Oitrus trifoliata Linn. Scott, Ga. ; Alwood, Ya. ; Gossard, Fla. 
Cornus alba Linn. var. sibirica Lodd. Britton, Conn. 
Cornus baileyi Coult & Evans. Gould (in N. Y.). 
Cornus sanguinea Linn. Britton, Conn. 

Cotoneaster sp.? Britton, Conn.; Lintner, Felt, X. Y. ; Card, R. I. 
Cotoneaster vulgaris Lindl. Alwood, Ya. 

« Report of the Connecticut Agricultural Experiment Station, 1902, Part II, 2d 
Report of the Entomologist, pp. 132-138. 



PLANTS COMMONLY OR BADLY INFESTED. 37 

Crataegus sp. Hawthorn. Britton, Conn.; Lintner, Felt, N.Y. ; Alwood,Va. ; Smith, 

N. J. » 

Oratsegus cordata Soland. Koehler, Conn. 

Crataegus oxyacantJia Linn. English hawthorn. Britton, Koehler, Conn. 
Oratsegus coccinea Linn. Koehler, Conn. 
Crataegus crus-galli Linn. Koehler, Conn. 
Cydonia vulgaris Pers. Common quince. Britton, Conn.; Lintner, N. Y. ; Ahvood, 

Va. 
Cydonia japordca Pers. Japanese or flowering quince. Britton, Koehler, Conn.; 

Lintner, X. Y. ; Alwood, Ya. ; Johnson, Md. 
Fagus sylvalica Linn. var. purpurea Ait. European purple-leaved beech. Smith, 

X. J. 
Juglans sieboldiana Maxim. Japanese walnut. Britton, Conn. ; Alw r ood, Va. ; Sher- 
man, X. C. ; Smith, N. J. 
Ligustrum vulgare Linn. Common privet. Alwood, Va. 

Populus sp. Poplar. Britton, Conn. ; Smith, N. J. ; Sanderson, Del. ; Felt, N. Y. 
Populus ddtoides Marsh. Carolina poplar. Britton, Conn.; Rolfs & Quaintance, 

Fla. ; Alwood, Ya. 
Populusnigra Linn. var. iialica Du Roi. Lombardy poplar. Britton, Koehler, Conn.; 

Rolfs & Quaintance, Fla. ; Alwood, Ya. 
Prunus amygdalus Stokes. Almond. Lintner, N. Y. ; Alwood, Ya. 
Prunus armeniaca Linn. Apricot. Lintner, Felt, X. Y. ; Alwood, Ya.; Smith, N.J. 
Prunus avium Linn. Sweet cherry. Britton, Conn.; Lintner, Felt, N. Y. ; Alwood, 

Ya.; Smith, N. J.; Cockerell, N. Mex. 
Prunus pumila Linn. Koehler, Conn. 

Prunus pumila var. besseyi Waugh. Sand cherry. Alwood, Ya. 
Prunus cerasifera Ehrh., var. atropurpurea Dipp. {P.pissardi). Purple-leaved plum. 

Britton, Conn.; Felt, N. Y. 
Prunus domestica Linn. European plum. Britton, Conn.; Alwood, Ya. 
Prunus hortulana Bailey. Wild goose plum. Alwood, Ya. 
Prunus -japonica Thunb. Flowering almond. Britton, Conn.; Felt, N. Y. 
Prunus maritima Waugh. Beach plum. Koehler, Britton, Conn. 
Prunus persica Sieb. & Zucc. Peach. Britton, Koehler, Conn.; Lintner, Felt, 

X. Y.; Alwood, Ya. ; Cockerell, X. Mex. 
Prunus triflora Roxbg. Japanese plum. Britton, Koehler, Conn.; Alwood, Va. 
Prunus serotina Ehrh. Koehler, Conn. 
Prunus virginiana Linn. Chokecherry. Koehler, Conn. 
Ptelea trifoliata Linn. Hop tree. Fernald, Mass. 
Pi/rus com munis Linn. Pear. Britton, Koehler, Conn.; Lintner, Felt, X. Y. ; 

Alwood, Va.; Cockerell. X. Mex. 
Pyrus sinensis Lindl. Sand pear, including Kieffer. Alwood, Ya. 
Pyrusbaccata Linn. Koehler, Conn. 
Pyrus malus Linn". Apple. Britton, Koehler, Conn.; Lintner, Felt, X. Y.: Alwood, 

Va. ; Doten, Nev.; Cockerell, X. Mex. 
Pyrus sp. Crab apple. Britton, Conn. 
Ribes oxyacanthoides Linn. Gooseberry, britton, Conn.: Lintner, Felt, N. Y.; 

Alwood, Va. ; Troop, Tnd. 
Ribes aureum Pursh. Missouri or flowering currant. Lintner, X. Y. 
Ribesrubrum Linn. Currant. Britton, Conn.; Lintner, Felt, N. Y. 
Ribes nii/rum Linn. Black currant. Alwood, Va. 

Zfosa sp. Britton, Conn.; Lintner, X. Y.; Alwood, Va.; Cockerell, X. Mex.; Bur- 
gess, Ohio; Troop, End.; Gould, Ml.; Scott, Ga. 
Rosa Carolina Linn. Koehler, Conn. 
Rosa luQida Ehrh. Koehler, Conn. 



38 THE SAN JOSE OR CHINESE SCALE. 

Rosa virginiana Mill. Koehler, Conn. 

Rosa rugosa Thunb. Britton, Koehler, Conn. 

Salix sp. Willow. Britton, Conn. ; Felt, N. Y. ; Sanderson, Del. 

Salix lucida Muhl. Koehler, Conn. 

Salix pentandra Linn. Laurel-leaved willow. Lintner, X. Y. ; Alwood, Va. . 

Salix vitellina Linn. Koehler, Conn. 

Salix babylonica Linn. Weeping willow. Lintner, N. Y. ; Alwood, Va 

Salix humilis Marsh. Koehler, Conn. 

Salix incana Schrank. Koehler, Conn. 

Sorbus sp. Mountain ash. Felt, N. Y. ; Hunter, Kans. 

Sorbus americana Marsh. American mountain ash. Britton, Koehler, Conn.; 

Alwood, Va. 
Sorbus aucuparia Linn. European mountain ash. Britton, Koehler, Conn. 
Sorbus melanocarpa C. Koch. (Aronia nigra Koehne). Black chokeberry. Koehler, 

Conn. 
Symphoricarpos racemosus Michx. Snowberry. Felt, N. Y. ; Smith, N. J. 
Syringa vulgaris Linn. Common lilac. Burgess, Ohio; commissioner of agriculture, 

N. Y. ; Troop, Ind. ; Alwood, Va. 
Syringa persica Linn. Persian lilac. Britton, Conn. 
Tilia sp. Basswood, linden. Britton, Conn. ; Lintner, commissioner of agriculture, 

N. Y. 
Tilia americana Linn. American linden or basswood. Britton, Conn. ; Alwood, Va. 
Toxylon pomiferum Raf . Osage orange. Britton, Conn. ; Lintner, Felt, N\ Y. ; 

Alwood, Va. 
Zllmus sp. Elm. Lintner, N. Y. ; Webster, Ohio; Troop,Ind. 
Ulmus americana Linn. American elm. Britton, Koehler, Conn. ; Alwood, Va. • 
Ulmus campestris Smith. English or European elm. Britton, Conn. ; Felt, N. Y. ; 

Smith, N. J. 

OCCASIONALLY OR RARELY INFESTED. 

Acer sp. Maple. Webster, Burgess, Ohio; Fernald, Mass. ; Butz, Pa. ; commissioner 

of agriculture, N. Y. 
Acer saccharinum Linn. Silver maple. Gould, Md. ; Alwood, Va. ; Hunter, Kans. ; 

Felt, N. Y. 
Acer saccharinum. Weir's cut-leaved. Felt, N. Y.- 
Acer platanoides Linn. Norway maple. Gould, Md. 
Actinid ia arguta Miq. (A. polygama) . Alwood, Va. 
JEsculus hippocaslanum Linn. Horse-chestnut. Felt, commissioner of agriculture, 

N. Y. ; Burgess, Parrot, Green, Ohio. 
Alnus sp. Alder. Felt, N. Y. ; Alwood, Va. 
Ampelopsis quinquefolia Michx. Virginia creeper. Alwood, Va. 
Betula sp. Birch. Felt, N. Y. 

Betula cdba Linn. Cut-leaved white birch. Britton, Conn.; Rolfs & Quaintance, Fla. 
Buxus sp. Box. Britton, Conn. 
Castanea americana Raf. Chestnut. Rolfs & Quaintance, Fla.; Alwood, Va. ; 

Felt, N. Y. 
Catalpa sp. Rolfs & Quaintance, Fla. 

Catalpa bignonioides Walt. Common catalpa. Alwood, Va. 
Ceanothus americanus Linn. Koehler, Conn. 
Celtis occidentalis Linn. Koehler, Conn. 
Cercidiphyllum japonicum Sieb. & Zucc. Britton, Conn. 
Citrus aurantium Linn. Gossard, Fla. 
Cornus allernifolia Linn. Koehler, Conn. 
Cornus stolonifera Michx. Koehler, Conn. 



PLANTS OCCASIONALLY OR RARELY INFESTED. 39 

Comus circinata L'Herit. Koehler, Conn. 

Cornus amomum Mill. Koehler, Conn. 

Cornus candidissima Marsh. Koehler, Conn. 

Cornus florida Linn. Commissioner of agriculture, Felt, N. Y.; Britton, Conn. 

Cornus florida. Red flowering. Alwood, Va. 

Deutzia sp. Fernald, Mass. 

Diospyros virginiana Linn. Persimmon. Lintner, N. Y. 

Elxagnus sp. Felt, N. Y. 

Elseagnus longipes Gray. Silver thorn. Commissioner of agriculture, N. Y. ; Scott, 
Ga. 

Eucalyptus sp. Felt, N. Y. 

Euonymus sp. Lintner, N. Y. ; Alwood, Va. 

Ficus carica Linn. Fig. Felt, N. Y. 

Forsythia sp. Commissioner of agriculture, N. Y. 

Fraxinus sp. Ash. Felt, N. Y. ; Butz, Pa. 

Fraxinus americana Linn. White ash. Hunter, Kans. 

Gleditschia triacanthos Linn. Honey locust. Britton, Conn. ; Sanderson, Del. ; com- 
missioner of agriculture, N. Y.; Johnson, Md. 

Hibiscus syriacus Linn. Shrubby althea. Smith, N. J. 

Hicoria pecan Britt. Pecan nut. Lintner, N. Y.; Alwood, Va. ; Scott, Ga. 

Juglans nigra Linn. Black walnut. Alwood, Va.; Rolfs & Quaintance, Fla. 

Juglansregia Linn. Persian or English walnut. Alwood, Va. ; Lintner, Felt, N. Y. ; 
Sanderson, Md. 

Kalmia lalifolia Linn. Mountain laurel. Felt, N. Y. 

Kerria japonica DC. Globe flower. Japanese rose. Felt, N. Y. 

Ligustrum ovalifolium Hassk. California privet. Britton, Koehler, Conn. 

Lonicera sp. Honeysuckle. Felt, N. Y. 

Morus sp. Mulberry. Alwood, Va. ; Burgess, Ohio; Johnson, Md. ; Scott, Ga. 

Moras sp. Tea's weeping mulberry. Taft, Mich. 

Physocarpus opulifolius Maxim. Koehler, Conn. 

Picea alba Link. White spruce. Fernald, Mass. 

Prunus cerasus Linn. Sour cherry. Felt, N. Y. ; Alwood, Va. ; Burgess, Ohio. 

Photinia villosa DC. Koehler, Conn. 

Rhpdotypos kerrioides Sieb. & Zucc. Koehler, Conn. 

Rhus sp. Sumac. Rolfs & Quaintance, Fla. ; Alwood, Va. ; Felt, N. Y. 

Rhus cotinus Linn. Smoke bush. Commissioner of agriculture, N. Y. 

Robinia sp. Locust. Sanderson, Del.; Burgess, Webster, Ohio; Johnson, Md. 

Rubus strigosus Michx. Red raspberry. Alwood, Va. ; Lintner, Felt, N. Y.; John- 
son, Md. 

Rubus nigrobaccus Bailey {R. villosus). Common blackberry. Lintner, Felt, N.Y.; 
Johnson, Md. 

Rubus villosus Ait. (R. Canadensis). Dewberry. Felt, N. Y. 

Sambucus sp. Elder. Commissioner of agriculture, N. Y. ; Fernald, Mass. ; Webster, 
Ohio. 

Sassafras officinale Nees. Sassafras. Sanderson, Del. 

Sorbaria sorbifolia A. Braun (Spirsea sorbifolia L. ). Britton, Conn. 

Spinca sp. Britton, Conn.; Lintner, Felt, N. Y. ; Alwood, Va. 

Thuya occidentalis Linn. Arborvitpe.' Fernald, Mass. 
Viburnum sp. Britton, Conn. ; Alwood, Va. 
Viburnum cassinoides Linn. Britton, Koehler, Conn. 
Viburnum opulus Linn. Koehler, Conn. 

Vitissp. Grapes. Britton, Conn.; Felt, N. Y.; Alwood, Va.; Butz, Pa.; Rolfs & 
Quaintance, Fla.; Johnson, Md. 



40 THE SAN JOSE OR CHINESE SCALE. 

NOT INFESTED. 

Ailanthus glandulosa Desf. Tree of heaven. 

Amorpha fruticosa Linn. 

Andromeda sp. 

Aralia spinosa Linn. Hercules' club. 

Aristolochia macrophylla Lam. Dutchman's pipe. 

Asimina triloba Dun. Papaw. 

Baccharis halimifolia Linn. Groundsel tree. 

Benzoin odoriferum Nees. (Lindera benzoin Blume). Spicebush. 

Berberis (all species). Barberry, including Mahonia. 

Bignonia sp. Trumpet vine. 

Calycanthus floridus Linn. Carolina allspice, sweet-scented shrub. 

Carpinus sp. Hornbeam. 

Cedrus sp. Cedar. 

Celastrus scandens Linn. Bittersweet. 

Cephalanthus occidentalis Linn. Buttonbush. 

Cercis canadensis Linn. Judas tree, redbud. 

Chamasdaphne calyculata Mcench. (Cassandra). Leather leaf. 

Chionanthus virginica Linn. Fringe tree. 

Cladrastis tinctoria Raf. , Yellowwood. 

Clethra alnifolia Linn. Sweet pepper bush. 

Corylus sp. Filbert, hazelnut. 

Daphne mezereum Linn. 

Diervilla sp. Weigela. 

Dirca palustris Linn. Leatherwood, moosewood. 

Exochorda grand/flora Lindl. Pearlbush. 

Gaylussacia sp. Huckleberry. 

Genista, tinctoria Linn. Dyer's greenweed. 

Ginkgo biloba Linn. Maidenhair tree. 

Gymnocladus canadensis Lam. Kentucky coffee tree. 

Halesia tetraptera Linn. Silver bell, snowdrop tree. 

Hamamelis virginiana Linn. Witch hazel. 

Hedera helix Linn. English ivy. 

Hicoria sp. (excepting H. pecan Britt). Hickory. 

Hydrangea (all species). 

Hypericum moserianum Andre. Gold flower. 

Ilex sp. 

Itea virginica Linn. Virginian willow. 

Jasminum nudiflorum Lindl. Yellow jasmine. 

Juglans cinerea Linn. Butternut. 

Juniperus sp. Juniper. 

Kcelreuteria paniculata Laxin. Varnish tree. 

Laburnum vulgare Griseb. Golden chain. 

Larix sp. Larch. 

Liquidambar styraciflua Linn. Sweet gum. 

Liriodendron tulipifera Linn. Tulip tree. 

Lycium hqlimifolium Mill. Matrimony vine. 

Magnolia (all species). 

Myrica cerifera Linn. Wax myrtle. 

Nyssa sylvatica Marsh. Tupelo, pepperidge, black gum, sour gum. 

Ostrya virginica Willd. Hornbeam, iron wood. 

Paulownia imperialis Sieb. & Zucc. 



PLANTS NOT INFESTED. 41 

Phellodendron sp. 

Philadelphus coronarius Linn. Mock orange, syringa. 

Pinus sp. Pine. 

Platanus occidental is Linn. American plane, button wood. 

Potent ilia fruticosa Linn . 

Querent; (all species). Oak. 

Retinispora (all species). Japan cypress. 

Rhamnus sp. Buckthorn. 

Rhododendron sp. 

Sciadopitys verticillata Sieb. & Zucc. Umbrella pine. 

Shepherdia sp. 

Smilax sp. 

Sophora japonica Linn. Japan pagoda tree. 

Staphylea sp. Bladder nut. 

Stephanandra flexuosa Sieb. & Zucc. 

Styrax japonica Sieb. & Zucc. 

Tamarix sp. 

Taxodium distichum Rich. Bald cypress. 

Taxus sp. Yew. 

Tecoma radicans Juss. Trumpet creeper. 

Tsuga canadensis Carr. Common hemlock. 

T 7 occmiit?77 sp. 

Wistaria sp. . 

Xanthoceras sorbifolia Bunge. 

Xanthoxylum americanum Mill. Prickly ash. 

Certain species have been reported as seriously infested in one part of the country 
and as exempt in other localities. Such plants have been placed in list No. 1. 
Quince is reported as being rarely infested, by Felt, of New York, and by Smith, of 
New Jersey. Sanderson writes that willows and poplars are not commonly infested 
in Maryland and Delaware, but in Connecticut willow hedges have been seriously 
infested, and young willow and poplar trees in nurseries have been thoroly incrnsted 
by the scales. Cockerell reports that osage orange is not infested in New Mexico 
tho much grown, and that Catalpa, elm, and walnut have not been found infested. 
Apricot, quince, and poplar are also reported as not being infested in New Mexico. 
Alwood, of Virginia, Burgess, of Ohio, and Felt, of New York, place the sour cherry 
(P. cerasus) in list No. 2, tho I have never found it infested in Connecticut. Burgess 
suggests that Kieffer pear be placed in the same list, but it is reported by Alwood as 
being badly infested in Virginia. Linden was placed in list No. 1 by the commis- 
sioner of agriculture of New York, while the hop-tree (Ptelea trifoliata) was placed 
in the same list by Fernald of Massachusetts. Elm was placed in list No. 1 by 
Webster in Ohio and Troop of Indiana. Smith, of New Jersey, finds European elm, 
purple-leaved beech, and Japanese walnut badly infested, while the common quince, 
cherry (except on Japanese stock), apricot, and poplar are not commonly infested. 
He has not seen the scale on birch, linden, persimmon, Catalpa, Acacia, or Buxus. 
Alwood, of Virginia, puts the common privet (L. vulgare) in list No. 1, while Koehler, 
in Connecticut, mentions it as one of the plants upon which he has not found the 
scale, tho growing near infested plants. Gossard, of Florida; Scott and Fiske, of 
Georgia, report Citrus trifoliata as being badly infested, while Alwood, of Virginia, 
places this plant in list No. 2. C. aurantium the common orange, is rarely infested, 
according to Gossard. 

In Connecticut the most commonly infested plants are apple, pear, peach, Japan 
plum, and currant among the fruits, tho sweet cherry, European plum, quince, and 
gooseberry are sometimes seriously injured. 



42 THE SAN JOSE OR CHINESE SCALE. 

The most commonly infested ornamentals are purple-leaved plum, Cratsegus, Japa- 
nese quince, mountain ash, red-twigged dogwood, and Rosa rugosa. Poplar, willow, 
Persian lilac, Cotoneaster, elm (both American and European), and osage orange 
have been found thoroly incrusted by the insects, especially when growing near 
infested trees. 

Of the plants which are reported as noninfested in this list 
probably many of them may be subject to slight or occasional 
infestation. Notwithstanding the San Jose scale's wide range of food 
plants, strangely enough certain varieties of pear seem to be almost 
never attacked, and are practically exempt from injury. This holds 
true also, to a less extent, with different varieties of other fruits. 
The striking illustrations are the Leconte and Kieffer varieties of 
pears, and the reason for this immunity is difficult to explain. Differ- 
ences in the density and texture of bark could hardly account for it, 
because that would scarcely protect new and comparatively tender 
growth. A notable instance of the immunity of the Leconte pear is 
seen in the little grove connected with the insectary of this Depart- 
ment. This grove has been thickly planted to pear and apple trees, so 
that the branches are interlacing all the time, and it has been pretty 
badly infested with the San Jose scale off and on for ten years, and 
yet the 10 or 12 Leconte trees have been clean the whole time, while 
the rest, representing different varieties of pear, apple, peach, and 
plum, have died out or have been replaced, some of them over and 
over again. 

CITRUS FRUITS AND THE SAN JOSE SCALE. 

The susceptibility of the orange and lemon and other citrus plants 
to the San Jose scale is a matter of great interest to citrus growers. 
In catalogs of the food plants of the San Jose scale the orange and 
lemon and other citrus fruits are listed, notably in Mrs. Fernald's 
Catalog of Coccida?. The facts on which this statement is based are 
rather meager, and, when examined, do not warrant any grave fears 
of injury to the ordinary cultivated citrus fruits. It is well known 
that the San Jose scale will infest rather freely the trifoliate orange, 
a hedge plant somewhat closely related to the orange and lemon. 
Some trifoliate trees, for example, on the Department grounds, are 
now rather thickly covered by the San Jose scale, but even in the case 
of this hedge plant the infestation is, as a rule, not serious, and, 
according to Mr. Gossard, the plant seems to throw the scale off as it 
grows. The first undoubted example of San Jose scale on orange was 
on certain hybrid sorts produced by crossing the trifoliate orange 
with the sweet orange, and was received in 1903 from Mr. Gossard 
from Florida. Mr. Gossard stated that in a single instance where a 
small sweet orange tree interlaced with the branches of a badly 
infested trifoliate orange the former had matured perhaps half a dozen 
San Jose scales. 



LIFE HISTORY. 43 

The second undoubted record is of material sent to Doctor Howard 
for determination by Dr. James Fletcher, entomologist of the Canadian 
Central Experimental Farm at Ottawa, who reported that the infested 
oranges sent had been forwarded to him from British Columbia and had 
been imported from Japan. These oranges, evidently of a mandarin or 
tangerine type, showed undoubted infestation with the San Jose scale. 
It is therefore evident that this scale insect may occasionally infest 
the orange, but the long coexistence of the San Jose scale and orange 
culture in southern California would seem to indicate the practical 
immunity of the orange tree from this scale pest. An earlier record 
of the San Jose scale on a citrus plant, by Mr. Cockerell, has always 
been under the question of a misidentification of the food plant. 

LIFE HISTORY. 

In common with all the armored scales, the life round of this insect, 
with the exception of a few hours of active larval existence and an 
equally brief winged existence in the case of the mature male, is past 
under the protection of a wax} 7 scale. This scale covering conceals 
the real insect beneath and prevents an} 7 easy observation or study of 
its life history. The San Jose scale has been under most careful 
observation by Mr. Pergande on potted plants in the insectary, and its 
history, which has hitherto been very imperfectly worked out, has been 
thoroly and carefully elaborated. 

The winter is past by the insects in a half : grown condition under 
small black protecting scales, mere points, just visible to the naked 
eye. The male scales are normally vastly in excess of the females, 
often representing 95 or more per cent. Early in April, in this lati- 
tude, the males transform to pupa? and emerge, and this gives the 
appearance of a sudden death of the great majority of these overwin- 
tered insects on the bark, and has led to some confusion in interpret- 
ing the effect of washes. The females at this period have arrived 
at the stage of impregnation, and the delicate two-winged males dis- 
appear after a few days. About a month later, varying with the cli- 
mate, the overwintered females come to full maturity and begin to 
give birth to a new generation, continuing to produce young for a 
period of upward of six weeks, when they reach the limit of produc- 
tion of young and perish. 

The adult female gives birth immediately to living young, differing 
in this respect from most other' scale insects. Ordinarily eggs are 
deposited beneath the scale, which in the course of a longer or shorter 
time hatch, and the young larva? make their escape and migrate to 
different parts of the plant. In the case of some scale insects the 
female fills its scale with eggs in the fall and perishes, the eggs win- 
tering over and hatching the foHowing spring. In others the insect 



44 



THE SAN" JOSE OR CHINESE SCALE. 



hibernates in the nearly mature condition, as does the San Jose scale, 
and deposits eggs in the spring or early summer. The viviparous 
habit, or the giving birth to the living young, possest by the San Jose 
scale, finds a parallel in many other insects and frequently in aphides. 
In the case of the San Jose scale the eggs are fairly well formed, 
a few at a time, within the bod}^ of the mother. What takes the place 
of the eggshell consists of a very delicate and thin membrane— the 
amnion — which incloses the developing larva and which at the moment 
of birth is cast off, and remains attached to or partly within the ovi- 
duct. The amnion is probably pushed out bj r the next larva in turn. 




Pig. 3. — Young larva and developing San Jose scale (Aspidiotus perniciusus): a, ventral view of 
larva, showing sucking beak with set* separated, with enlarged tarsal claw at right; b, dorsal view 
of same, still more contracted, with the first waxy filaments appearing; c, dorsal and lateral views 
of same, somewhat contracted, illustrating further development of wax secretion; d, later stage of 
same, dorsal and lateral views, showing matting of wax secretions and first form of young scale. 
All greatly enlarged (from Howard and Marlatt). 

The difference between this mode of birth and the ordinary method 
thru the medium of true eggs is simply that what corresponds with 
the egg is retained b} r the female until the larva is developed, instead 
of development of the larva progressing after the egg leaves the 
parent. 

The emergence of the young from the female over a period of six 
weeks leads to a very confusing intermingling of generations and 
renders it difficult to make observations on the life history except by 
isolating and watching individuals. By means of such isolation of 
individuals, however, we have been able to most carefully trace the 



LIFE HISTORY. 45 

different generations. The course of the development of a single 
generation follows: 

After being expelled the larva remains motionless for a little while, 
with antennas and legs folded beneath the body. It soon hardens 
enough to run about, and, forcing its way out from beneath the pro- 
tecting scale of the mother, scurries over the plant to find a suitable 
place to settle. 

The newly born larva (fig. 3, a) is an almost microscopic creature of 
pale orange-yellow color, with long oval bodjr, and with the customaiy 
six legs and two feelers. The long thread-like proboscis with which 
the juices of the plant are sucked up is doubled on itself and lies in an 
invagination of the body wall, the tip only projecting. 

After crawling about for a few hours the } T oung larva settles down 
and slowly works its long bristle-like sucking beak thru the bark, 
folds its antenna? and legs beneath its body, and contracts t,o a nearly 
circular form. The development of the scale begins even before the 
larva becomes fixt. The secretion starts in the form of very minute 
white fibrous waxy filaments, which spring from all parts of the body 
and rapidl3 T become more numerous and dense (fig. 3, b, c). At first the 
orange color of the larva shows thru the thickening downy white 
envelop, but within two days the insect becomes entirely concealed by 
the white or pale grayish yellow shell or scale, which now has a promi- 
nent central nipple (fig. 3, d), the younger ones often possessing instead 
a central tuft. The scale is formed by the slow matting and melting- 
together of the filaments of wax. During the first day the scale appears 
like a very microscopic downy hemisphere. The matting of the secre- 
tion continues until the appearance of down and individual filaments is 
entirely lost and the surface becomes smooth. In the early history of 
the scale it maintains its pale whitish or grajdsh 3^ellow color, turning 
gradually darker gray, the central nipple remaining lighter colored 
usually thruout development. 

The male and female scales are exactly similar in size, color, and shape 
until after the first molt, which occurs twelve days after the emergence 
of the larva. With this molt, however, the insects beneath the scale 
lose all resemblance to each other. The males (fig. 4, a) are rather larger 
than the females and have large purple eyes, while the females have lost 
their ej^es entirely. The legs and antenna} have disappeared in both 
sexes. The males are elongate and pyriform, while the females are 
almost circular, amounting practically to a flattened sac with indistinct 
segmentation, and without organs, except a long sucking bristle 
springing from near the center beneath. The color of both sexes is light 
lemon-yellow. The scales at this time have a decidedly grayish tint, 
overcast somewhat with yellow. 

Eighteen days from birth the males change to the first pupal condi- 
tion (pro-pupa) (fig. 4, £), and the male scales assume an elongate oval, 



46 



THE SA2ST JOSE OR CHINESE SCALE. 



sometimes slightly curved, shape, characteristic of the sex, the exuvia 
or cast larval skin showing near the anterior end. 

The male pro-pupas are very pale yellow, with the legs and antennas 
(which have reappeared), together with the two or three terminal seg- 
ments, colorless. The eyes are dark purple and placed close together. 
The antenna? are stout and bent closely along the edge of the body as 
far as the first pair of legs, where they curve slightly inward. Promi- 
nent wing pads extend along the sides of the body. The terminal 
segment bears two short spines. 

The female undegroes a second molt about twenty days from the 
larva. At each molt the old skin splits around the edge of the bodj^, 
the upper half adhering to the covering scale and the lower forming a 
sort of ventral scale next to the bark. This form of molting is com- 
mon to scales of this kind. 




Fig. 4.— Development of male San Jose scale (Aspidiotus perniciosas): a, ventral view of larva after 
first molt; &, same after second molt (pro-pupa stage); c and. d, true pupa, ventral and dorsal views. 
All greatly enlarged (from Howard and Marlatt). 

The covering scales at this stage are of a more purplish gray, the 
portion covering the exuvias inclining to yellowish. The male scales 
are more yellowish than the female. The effect of the sucking of the 
insects is now quite apparent on the young growth, causing the bark 
to assume a purplish hue for some distance around the central portion, 
contrasting strongly with the natural reddish green of the uninjured 
bark. With the second molt the females do not change materially 
from their former appearance^ retaining the pale yellow color with a 
number of transparent spots around the edge of the body. The suck- 
ing bristles are extremely long, two or three times the length of the 
body of the insect. The only distinctive features are in the last seg- 
ment and are noted in the technical description. 

About twenty days after birth the male insect transforms to the 
true pupa. With the first molt the shed larval skin is retained beneath 
the scale as in the case of the female; with the later moltings the shed 
skins are pushed out from beneath the scale. The scale after the 



LIFE HISTORY. 



47 



second molt presents on the inside two longitudinal ridges running 
from one end to the other, touching the sides of the pupa, and which 
apparently enable the insect to move backward or forward and assist 
the imago in pushing itself out. 

The true pupa (fig. 4, c, d) is pale yellow, sometimes purplish, darkest 
about the base of the abdomen. The head, antenna?, legs, wing pads, 
and style are well formed, but almost colorless. The antennae reach 
as far back as the second pair of legs and are not curved under, as 
formerly, but lie close to the sides of the body with the ends free. 
The first pair of legs is held forward, reaching slight^ beyond the 
eyes, the middle femora projecting somewhat beyond the margin of 
the abdomen. The hind legs are inclined backward and reach to the 
end of the body. The style is rounded at tip, conical, and about as 
long as the posterior tibiae. 




Pig. 5. — Aspidiotus pernidosus: adult male, greatly enlarged (from Howard and Marlatt). 

From four to six days later, or from twenty-four to twenty-six days 
from birth, the males mature and back out from the rear end of their 
scales, having previously, for a day or two, remained practically 
developed but resting under the scale. They seem to issue chiefly b}'' 
night or in the evening. 

The mature male (fig. 5) appears as a delicate two-winged fly-like 
insect with long feelers and a single anal style projecting from the end 
of the body; orange in color, with a faintl} 7 dusky shade on the pro- 
thorax. The head is darker than the rest of the body, the eyes are 
dark purple, and the antenme, legs, and style are smoky. The wings 
are iridescent with yellow and green, very faintly clouded. 

Thirty days from birth the females are full grown and the embryonic 
young may be seen within their bodies, each inclosed in a delicate 
8449— No. 62—06 4 



48 



THE SAN JOSE OE CHINESE SCALE. 



membrane. At from thirty-three to iorty days the larva? again begin 
to make their appearance. 

The adult female, prior to the development of the young, measures 1 
millimeter in length and a little less in breadth, and is pale yellow, with 
transparent spots near the margin of the body (fig. 6). 

The length of a generation is determined by the female and, as 
shown by the above record, covers a period of from thirty-three to 
forty days. Successive generations were followed carefully thruout 





F IG . 6.— Adult female San Jose scale {Aspkliotus pernicwsus) before development of eggs: a, ventral 
view, showing very long sucking setse; b, anal plate, showing characteristic ornamentation of edge. 
Greatly enlarged (from Howard and Marlatt). 

the summer, and it was found that at Washington four full generations 
are regularly developed, with the possibility of a partial fifth genera- 
tion. On a number of potted trees a single overwintered female was 
left to each tree. After the full progeny of this individual had gone 
out over the tree, all were removed again, except one of the oldest and 
fertilized females. This method was continued for each generation 
thruout the breeding season. Some interesting records, tabulated 
below, were thus obtained, which indicate the fecundity of the females 
as well as the number of generations. 



LIFE HISTOKY. 
Record showing fecundity of San Jose scale. 



49 



Number of tree. 



1 

3 
1 
5 
6 

7 

1 

3 

4 
5 



Males. 



Females. Total. 



Progeny of overwintered 

females. 

106 
120 
198 
40 
158 
58 
13 



72 


31 ' 


77 


13 


138 


60 


18 


22 


98 


00 


33 


25 


13 




ni/fii 


j of second 



o.tion. 
350 235 
276 226 
325 92 



192 
115 
206 



120 
151 
124 



585 
502 
417 
312 
556 
330 



Number of tree. 



1 
2 
3 
4 
5 
6 

1 
2 
3 

1 
5 



Males. Females. Total. 



Progeny 

110 
122 
190 
187 

174 
107 

J'rniii nil 

242 
112 
92 
210 
242 
156 



of Hi in! 
tiou. 
307 
464 
284 
400 
280 
274 

of fourth 

tin II. 

319 

230 
170 
344 
313 
293 



in a, ra- 
in 
>,,; 
474 
587 
454 
354 

genera- 
mi 
342 
262 
554 
585 
419 



Perhaps the most notable feature of the foregoing- records is the 
result obtained from the overwintered females. It will be seen that 
the males greatty predominate in this generation, and that the numbers 
of both sexes are insignificant compared with the progeny of the later 
generations. The males still predominate in the second generation, 
but in the third and fourth generations the females considerably out- 
number the males, in one instance the females from a single mother 
reaching the astonishing number of 464, which, with 122 males from 
the same parent, makes the progeny of this female 586 insects. Tak- 
ing 200 females as an average of the different generations for the 
year, the product of a single individual from spring to fall amounts to 
1,608,040,200 females. In one instance we have over 415 males from 
a single female, and while the number of males would average some- 
what less than the females, taking the summer thru, } T et, having 
underestimated the females, the males may be estimated at the same 
number, giving a total of 3,216,080,400 descendants from a single 
insect in a single season. It is not to be expected, of course, that all 
the individuals from a scale survive and perform their function in life, 
but under favorable conditions, or in the case of a tree newly infested 
or not heavity incrusted, the vast majority- undoubtedly go thru their 
existence without accident. Neither the rapidity with which trees 
become infested nor the fatal effect which so early follows the appear- 
ance of this scale insect is therefore to be wondered at. 

Owing to the long period during which the female is continuously 
producing young the different generations or broods in the course of the 
summer are not distinctly markedand merge insensibly into each other — 
so much so that at almost any time there will be found young larva- 
running about over the trees and scales in all stages of development. 
►Still, at certain times the .young will be noticeably more abundant, 
indicating periods when the majority of each generation are producing 
young. In this latitude the first young appear, as noted, by the middle 



50 THE SAN JOSE OR CHINESE SCALE. 

of May; at Amherst, Mass., they were first noticed June 12, and in 
Arizona they are recorded as appearing - in March. The larvse are con- 
tinuously present on the trees until further hatching is prevented by 
severe frosts. In 1894, as we have already shown on page 289 of Vol- 
ume VII of Insect Life, the first frosts at Washington oocurred in the 
latter part of October and the hatching of the young ceased before the 
1st of November. October 24, 1894, however, Doctor Howard saw 
recentty settled larvae, not more than 5 da}^s old, at Lewisburg, Pa. In 
1895 the October frosts were insignificant, and in this neighborhood 
no severe frost occurred until about the 1st of December. The result 
was that young larvae were found at Washington until late in Novem- 
ber, while on twigs received from Chestertown, Md. , November 13 and 
November 2T, the young were more or less abundant. The cold spell 
of the last week in November and the first week in December pat a 
stop to development here. This same cold spell was of very wide 
extent. As far to the southwest as San Antonio, Tex., the thermom- 
eter dropped to 31° on December 3. A similar, or even lower, tem- 
perature was noted at New Orleans, yet on December 16 Doctor 
Howard found newly hatched young, less than 24 hours old, upon a 
plum tree at Audubon Park, New Orleans. 

In autumn, or when further development is stopt by cold weather, 
hibernation is begun by scales in all stages of development, from the 
white, minute, down-covered recently hatched young to the mature and 
full-grown females and males. Unquestionably many young perish 
during the winter, and normally in spring quite a percentage of the 
smaller or half-grown scales will be found to have perished. It is 
veiy probable that many females have union with the males in the fall, 
but the majorit} 7 of them are uiiquestionabl} r immature, and are fertil- 
ized in this latitude early in April by overwintered males which, as we 
have noted, appear nearly a month before the first young of the spring- 
brood. 

The actual rate of the production of young at different periods of 
the life of the adult female has not been determined with accuracy. 
As the average reproducing period of the adult female is six weeks, 
and as the average number of young from each female is about 400, 
there must be born from 9 to 10 young every twenty-four hours. The 
great labor of watching an individual female and removing every 
twenty-four hours the young she has given birth to during that period 
has not been entered upon. Sufficient observations have been made, 
however, to indicate that the main period of reproductive activity is 
the second or third week after the female has reached maturity. At 
first the young are born with less frequency, and there is a correspond- 
ing reduction in reproductive activity toward the end of the life of the 
individual. The young*are born indifferently by day or by night, per- 
haps more during the day than during the night. In the morning. 



DESCRIPTIONS OF SCALE AND INSECT. 51 

however, examination of the trees under observation always shows 
many migrating young which must have been born daring the night, 
while observations at nightfall show always as many, and frequently 
more, which have been born during the day. 

The gradual production of the young by the female has an important 
bearing on the question of remedies, and the old washes, which aimed 
at the destruction of the young as soon as they emerge from the females, 
are rendered almost valueless because, to make them effective, it is 
necessary to repeat them many times during a period of six weeks. 
Within two or three days after hatching the young larva? will have 
formed a scale which will be impervious to these weaker washes. 

The larva does not ordinarily travel far from the parent insect, and 
usually rests within a few inches of the old scale or at the first avail- 
able point. The}' will not, so far as observed, travel very far from 
the base of the tree, and in the potted trees none were observed to go 
more than 2 inches from the base of the trunk. 

DESCRIPTIONS OF SCALE AND INSECT. 

Scale of female. — The scale of the female is circular, very slightly 
raised centrally, and varies in diameter from 1 to 2 mm , averaging about 
l.-± mm . The exuvia is central or nearly so. The large, well-developed 
scales are gray, excepting the central part covering the exuvia, which 
varies from pale to reddish yellow, altho in some cases dark colored. 
The scale is usually smooth exteriorly or sometimes slightly annulated, 
and the limits of the larval scale are always plainly marked. The 
natural color of the scale is frequently obscured by the presence of 
the soot}' fungus (JFumago salicina). 

Scale of male. — The mature male scale is oblong-oval, nearly twice as 
long as wide, and averaging in length about half the diameter of the 
female scale. The position of the larval scale is marked by a nipple- 
like prominence located between the center and the anterior margin 
of the scale. The scale of the male is usually darker than that of the 
female, sometimes black, but often gray, the larval scale covering the 
exuvia very f requentty light yellow, as with the female. Not uncom- 
monly the circular scale, formed prior to the first molt, is black, while 
the later additions, giving it its oblong shape, are gray. 

The scale covering of the hibernating insects in winter is black, and 
on the bark in summer also the scale coverings dark or often black- 
ened by the sooty fungus referred to. But the normal color of the 
scale of both female and male is light, and on the leaves of pear, for 
example, the male scales are often a very light buff, and present such 
a marked contrast to the winter appearance that no one would suspect 
them of belonging to the same insect. 

Egg. — The egg j s never (or rarely) extruded as such by the female. 
and as it exists within the body of the mother is a mere amniotic mem- 



52 THE SAN JOSE OR CHINESE SCALE. 

brane, and the forming 1 embryo showing- through gives it a yellowish- 
white color. The embryo with the envelop measures about 0.2 mm long 
by ().l mra wide. 

Newly hatched larva. — The young larvae of both sexes are alike, and 
are pale orange in color, with long oval bodies. They measure in length 
about 0.2-A mm by 0.1 mm in width. The sucking bristles are normally 
doubled on themselves, but when unfolded are nearly three times the 
length of the body. The antennae are apparently hVe-jointed, the last 
two joints being much longer than the others, slender, subequal in 
length, and both finely and distinctly annulated. The last joint bears 
a small nipple-like projection near the tip. The head is somewhat con- 
cave in front, and the eyes are nearby transparent and slightly purplish. 
The terminal segment of the abdomen foreshadows in structure the 
plates and spines of the adult female. The large central plates each 
terminate in a long hair. The tarsus is represented by apparently a 
single, strong, slightly curved claw. The tip of the tibia bears exteri- 
orly two rather long capitate hairs, and two similar hairs project also 
from the inner extreunhVy. Other details of structure are shown in the 
illustration. 

Larva of the second stage. — After the first molt the difference in the 
sexes becomes apparent, altho the covering scales are still identical. 

The female insects are somewhat smaller than the males at this stage. 
The e} T es, legs, and antennae in this sex have entirely disappeared: The 
form is almost circular, flattened. The color is j^ellow, with irregular 
transparent spots appearing in different parts of the body. 

The males are somewhat larger than the females, elongate, pyriform. 
The eyes are prominent, purple in color. The legs and antennae, as 
with the females, are wanting. The general color of the body is 
j^ellow, with the irregular transparent spots noted in the case of the 
female. The greatest diameter in both sexes is less than one-half a 
millimeter, and in the characteristics of the terminal segment both 
agree, practically, with the adult female. 

Male pro-pupa. — With the second molt the male assumes a form 
foreshadowing the true pupa, which may be called the pro-pupa. a 
The form is elongate oval; length 0.5 ram . The color is very pale 
yellow, with the antennae, limbs, and wingpads, and two or three ter- 
minal segments of the abdomen, colorless. The legs and antennae, as 
noted, have reappeared, and also prominent pads foreshadowing the 
wings of the adult. The eyes are dark purple and placed close together. 
The antennae are very stout, and curved closely around the edge of 
the bodjr as far as the anterior legs, where they bend inward. The 

« The existence of a pro-pupa or a first pupal stage in the Coccidte analogous to 
the first pupal stage of higher Hemiptera has also been affirmed by Dr. Fr. Loew. 
(Wiener En torn. Zeit., Jan., 1884, p. 13.) 



DESCRIPTIONS OF INSECT. 53 

wing-pads are stout and almost entirely cover the abdomen. The ter- 
minal segment is still broad and flattened and bears two short spines, 
but the other characters have disappeared. 

True pupa of male. — The true pupa resembles the previous stage, 
except that the members are longer and slenderer, and the prominent 
anal style has appeared. The pupa is pale }^ellow and purplish in 
color, darkest about the base of the abdomen, the head, antennae, legs, 
wing sheaths, and style being almost colorless and transparent. The 
eye spots are dark purple. The antennae extend nearly to the middle 
femora, and are not curved under the body as formerly, but are applied 
close to the sides with the apex free. The anterior legs are held for- 
ward, reaching slightly beyond the eyes. The middle femora rest 
transversely to the body, projecting somewhat beyond the margin of 
the abdomen, while their tibise form with them a right angle and reach 
nearly to the apex of the hind femora. The latter incline posteriorly, 
while the hind tibiae are applied close to the sides of the body, except 
toward the tip, and reach nearly to the base of the style. The style is 
rather stout, conical, obtusely pointed at tip, and about as long as 
posterior tibiae. Length, 0.8 mm , including style, which measures about 
0.15 mm . 

Mature male. — The general color is orange with a faint duskiness on 
the prothorax. The head is somewhat darker than the rest of the 
body. The eyes are dark purple, almost black. The antennae are 
yellow, somewhat obscure or smoky. The legs and style are dusky, 
the latter paler than the former. The thoracic shield is regularly 
ovoid, compressed anteriorly, dusky in color, with margin brown, more 
distinctly so anterior^; transverse band narrow, brown. Antennae 
10-jointed, two basal joints shortest, second nearly globular, inserted 
in the first; joints 4 and 5 subequal, longer than any of the others; 
joint 6 next in length, and joints 3, 7, and 9 shorter and subequal; 
joint 10 still shorter, conical. Antennae somewhat hairy and nearly as 
long as the body of the insect. Wings faintly dusky, iridescent with 
yellow and green. Length of body about 0.6 ram ; style, 0.25 mm . 

Female, third stage. — After the second molt the females still appear 
pale3 T ellow as before, with various larger and smaller transparent spots 
around the border of the body. The form is nearly circular, with 
greatest diameter averaging 0.56 mm . The sucking bristles are very 
prominent and long, three times the length of the insect. The last 
segment in this stage has practically the characters of the mature female, 
as follows: There are two pairs of lobes, the terminal ones largest and 
nearty three times as broad as the other lobes. Terminal lobes are 
rounded at the apex and are distinctly notched near the middle of the 
external edge. The second pair of lobes is smaller and narrower, and 
is also notched externally. Between the first and second lobe on either 



54 THE .SAN JOSE OR CHINESE SCALE. 

side is a small spine, and two or three such spines are just back of the 
second lobe, while back of these are three stout teeth curving anteri- 
orly. A still smaller blunt tooth sometimes occurs near the middle of 
the lateral margin. The segmentation of the body at this stage is 
quite distinct. 

Mature female. — After reaching maturity the embryonic young are 
at first not visible, but later the body becomes filled with them. The 
mature female measures 0.8 mm wide by about l mm long. a 

The following description of this stage is reproduced from Comstock: 

The body of the female is yellowish and almost circular in outline; the segmenta- 
tion is distinct, tho not conspicuous. The last segment presents the following 
characters : 

There are only two pairs of lobes visible; the first pair converge at tip, are notched 
about midway their length on the lateral margin, and often bear a slight notch on 
the mesal margin, near the tip. The second pair are notched once on the lateral 
margin. 

The margin of the ventral surface of the segment is deeply incised twice on each 
side of the meson, once between the bases of the first and second lobes, and again 
laterad of the second lobe. On each side of each of these incisions is a club-shaped 
thickening of the body wall. 

There are two inconspicuous simple plates between the median lobes, and on each 
side similar plates extending caudad of the first incision, three small plates' serrate 
on their lateral margin caudad of the second incision, and the club-shaped thicken- 
ings of the body wall bounding it, and three wide prolongations of the margin 
between the third and fourth spines. These prolongations are usually fringed on 
their distal margins. There are also, in some, irregular prolongations of the margin 
between the fourth spine and the penultimate segment. 

The first and second spines are situated laterad of the first and second lobes, 
respectively; the third spine laterad of second incision, and the fourth spine about 
one-half the distance from the first lobe to the penultimate segment. 

SYSTEMATIC POSITION AND RELATIONSHIPS. 

The San Jose scale was described by Professor Comstock from 
material collected in 1880 in Santa Clara County, Cal., on apple, pear, 
plum, and other fruit trees. 6 The relationships of this scale insect 
have been discust by various authors, notably b}^ Prof. T. D. A. Cock- 
erell, without, however, reaching a very good solution, in the judg- 
ment of the writer. Without going into a detailed technical discus- 
sion, the San Jose scale is quite as closely allied in structure, scale 
covering, and habit with the Aonidiella group as it is with the group 
including ancyhos and ostreeeformis. It is a very distinct and well- 
marked species, however, and is always eas}^ of identification after one 
becomes once familiar with its principal characteristic structural fea- 
tures, and it is one of the few scale insects which can ordinarily be 

«Rept. U. S. Dept. Agric, 1880, p. 304. 

6 Report of the Entomologist, in the Report of Commissioner of Agriculture for 
1880 (1881), pp. 304, 305. 



SYSTEMATIC POSITION AND RELATIONSHIPS. 55 

safely identified from the appearance of the scale covering and with- 
out being prepared for microscopical stud}^. 

Three varieties of the San Jose scale have been designated, none of 
which are valid. Of these Aspidiotus perniciosus var. albopunctatus 
Ckll. was described from twigs of a supposed orange seedling sent 
from Japan and stopt b}^ Mr. Craw in his quarantine work in San 
Francisco. The twigs are thorny and ma} r possibly be of the trifoliate 
orange or of some orange seedling, but whether of ordinary orange 
or tangerine or some other horticultural variety can not be determined. 
From the extreme unlikelihood of the San Jose scale attacking ordi- 
nary orange, the probability is very strong that these seedlings were 
either trifoliate or of the mandarin or tangerine tjpes. At any rate, 
the scale itself is typical San Jose scale, and there is no basis what- 
ever for tl e .separation of these specimens as a variety. The character 
on which the variety was founded, namely, the white dot surrounded 
by a black ring marking the exuvia, is a feature which may be very 
commonly found in the San Jose scale from any source. 

The other variety established by Mr. Cockerell is his Aspidiotus 
perniciosus var. andromelas, first described in California Fruit Grower, 
June 5, 1897, on a plant labeled " ' Plimtenia glauca" from Japan, also 
received from Mr. Craw. This variety is also based on the character 
of the covering scale, and is described as wholly black without any 
light dot and ring, a condition which is easily produced by rubbing or 
otherwise accidentally and may occur anywhere. 

A third synonym of the San Jose scale is MaskelFs species Aspi- 
diotus fiisea, described in the New Zealand Transactions, Volume 
XXVII, page 43, 1894, figures 6-9, Plate I. This insect was described 
from material collected in Australia on peach; and from Maskell's own 
figures and account of it, and also from the study made b} r Leonardi 
in Italy, and from the later note on the subject by Maskell himself in 
the Canadian Entomologist, it is evident that this species was based 
on material representing the last stage of the female of perniciosus, 
but before the secretionary supplement had been much if any devel- 
oped, so that the second exuvium was still larger than the newly 
molted insect. This point can not, of course, be fully determined 
without an examination of type material, but there is very little doubt 
in the writer's mind of the correctness of this reference. 

A fourth variety is Aspidiotus perniciosus var. eucalypti Fuller. 
A studv of material received from Fuller of this variety indicates that 
it should not be referred to the San Jose scale at all, but is a good 
distinct species belonging to the genus Aonidiella, and the name 
becomes Aonidiella eucalypti Fuller. 

No valid varieties or subspecies of the San Jose scale have therefore 
been found, and all of the points of infestation now known can be 
traced directly to the Chinese origin of the scale. 



56 THE SAN JOSE OR CHINESE SCALE. 

MEANS OF DISTRIBUTION. 

From an economic standpoint the important considerations in the 
means of spread of this insect are those which affect its wide distribu- 
tion from one part of the country to another. The transportation by 
nursery stock or scions or budding and grafting material, as indicated 
in the foregoing account of this insect, is unquestionabty the usual 
and principal means of carrying the insect to a distance. The impor- 
tance of this means of distributing various insects has only been fully 
realized in this country in the last few years, but the present instance 
and some other notable ones of like nature have emphasized the great 
danger incurred not only in the indiscriminate introduction of plants 
from foreign sources, but also in the carriage of plants from one part 
of the country to another without competent inspection. 

The San Jose scale is also frequentty carried about on fruit, par- 
ticularly of the apple and pear. The young scale insect goes ont on 
the fruit, and in the case of badly infested trees there is usually a good 
deal of scale on the fruit particularly, massed at the blossom and stem 
ends. The scale may go on breeding on such fruit and the young may 
be found crawling about on the fruit and in the boxes. Such fruit is 
commonly shipped to remote points, and infested fruit may be found 
quite commonly in the markets of this country ; and when attention 
was drawn to the San Jose scale by its first developing in the East, 
infested fruit from California could be found in almost any of the 
fruit markets of the principal eastern cities. 

The shipping of infested fruit from California had been going on 
for a great many years, and in spite of its wide dissemination in this 
country, and to some extent abroad, there is not, so far as the writer 
knows, a single authenticated instance of the scale having been estab- 
lished from such material. The possibility of it, however, undoubt- 
edly exists, but the danger seems to be inconsiderable. The fruit is 
eaten in such places and the parings and waste material are usually 
disposed of in such a way that it would be very exceptional indeed for 
such fruit, or the young scale that might hatch on them, to get access 
to trees on which the scale could make lodgment. It would practi- 
cally be necessary for the parings to be tied to a tree, or the fruit to 
be placed in the crotches of the tree, to secure infestation, and it is 
the belief of the writer that infestation from this source can be prac- 
tically ignored. This has an important bearing on the legislation 
against American fruits enacted by various foreign countries, and cer- 
tainly the history in this regard in the United States is well worth 
considering where such fruit was shipped about for years prior to the 
San Jose scale scare without restrictions. The wide distribution, 
therefore, of the San Jose scale is substantially limited to its carriage 
on nursery stock and cuttings. 



MEANS OF DISTRIBUTION. 57 

The local spread of the insect from orchard to orchard and from 
tree to tree must also be brought about thru the agenc} T of means 
other than those under the control of the insect itself. The female is 
wingless and after once becoming fixt can not move. The young lice, 
as before stated, are active, crawl rapidly, and may reach other trees, 
but this is rare unless the limbs interlace, since we have shown by 
breeding-cage experiments that the larvae normally crawl but a few 
inches. Such spread, however, is comparatively insignificant except 
in the case of nursery stock, which is grown close together. It is 
possible that strong winds may carry the young bodily from one tree 
to another, or they may be floated on water to distant points, particu- 
larly in irrigated districts, but the principal method of the spread of 
these young lice is by means of other insects and b}^ birds. The active 
young lice soon crawl upon any small winged insect, particularly if 
the latter be of a dark color, and may thus be carried considerable 
distances. They are frequently found crawling upon ants, which are 
great travelers. It is extremely probable that they also crawl upon 
the feet of birds, and may be transported by these carriers for man} 7 
miles. 

Some interesting observations have been made by Mr. Schwarz upon 
the transporting of these scale larvae by other insects. A little black 
ladybird, Microweisea (Pent-ilia) misella Lee, which was very active 
in devouring scale larva?, was unfortunately equally efficient in trans- 
porting many of these young lice to other parts of the tree or to other 
trees; in fact, it was difficult to find a single beetle which did not carry 
on its back at least one larva of the San Jose scale, and sometimes three 
or four were found upon a single wing cover of a beetle. The small 
black ant, Monomoriurn minutum Mayr, was particularly abundant 
upon pears, attracted by the juices emerging from cracks, and almost 
every one of these insects carried on its back one or more specimens 
of the young scale insects. Specimens of the little chrysomelid beetle 
Typophorus canettus Fab. were also found upon the trees. Both red 
and black specimens of this beetle occurred, and the interesting obser- 
vation was made that while Aspidiotus larvae crawled freely on the 
black individuals, no specimens were to be found upon the red ones. 
The same peculiarity was found to hold true with the ants. The red 
ant, Formica schaufussi Ma} 7 r, was abundant upon the pears, but no 
specimens were found bearing Aspidiotus larva?, while, as just stated. 
the little black Monomoriurn was always found carrying them. 

As illustrating this transportation of the scale by birds or insects 
the experience at Riverside, Md. (Bui. 3, p. 25), may be cited, and 
Professor Smith reports a similar instance in New Jersey, in letter of 
January 13, 1896. 

In spite of the abundance of insects which may transport the larvae 
the progress of the scale from infested trees to noninfested trees is 



58 THE SAN JOSE OR CHINESE SCALE. 

slow where trees are moderate^ widely separated, and usually an 
entire orchard will not become affected from a single original point 
for several years. 

Occasionally the young scales may be locally transported by men or 
teams. An interesting case in point is given by Professor Rolfs. He 
states that some-melons growing in an infested orchard were given by 
the owner to a friend, who took them away from the orchard in his 
wagon. A year later the scale developed on a tree under which the 
team had been hitched while the melons were unloaded. As this 
orchard was entirely free from the scale originally, it seems to be a 
reasonable inference that the young had crawled upon the wagon, 
harness, or melons, were eonvej^ed a distance of 3 miles, and suc- 
ceeded in gaining access to a tree which probably touched the wagon 
or team during the interval of unloading. 

PARASITES AND OTHER NATURAL ENEMIES. 

The following paragraphs, under the heading Ck True parasites," 
were prepared for this bulletin by Dr. L. O. Howard. 

TRUE PARASITES. 

Some eight species of true parasites have been reared from the San 
Jose scale in this country. Nearly all of these are widespread, occur- 
ring on the Pacitic coast, and generally also in the East, and are found 
also in other parts of the world. None of them are specific enemies 
of the San Jose scale in the sense that they are limited to this species 
of scale, but all of them are general parasites on other armored scale 
insects. They are as follows: 

Aphelinus fuscipennis Howard. 

Aphelinus mytilaspidis Le Baron. 

Aspidiotiphagus citrinus Howard. 

Anaphes gracilis- Howard. 

Physcus varicornis Howard. 

Prospalta aurantii Howard. 

Ablerus clisiocampx Ash mead. 

Rhopoideus citrinus Howard. 
Of these Aspidiotiphagus citrinus, Prospalta aurantii, Aphelinus 
fuscipennis, and Aphelinus mytilaspidis are of very wide distribution. 
Aspidiotiphagus citrinus, for example, originally described from Cali- 
fornia in 1891, is now found in many other portions of the United 
States, in the West Indies, Italy, Austria, Ceylon, China, Formosa, 
Japan, Cape Colony, Queensland, South Australia, and Hawaii, and 
this remarkable distribution is practically followed by the other three. 
The most important of these parasites is the little Aphelinus fusci- 
pennis. It was reared in large numbers by Mr. Coquillett, in Califor- 
nia, man}' years ago, where it was found to breed thruout the year, 



TRUE PARASITES. 59 

specimens being reared as late as November 10. It was subsequently 
reared man}?- times by Mr. Alexander Craw, Mr. E. M. Ehrhorn, and 
others, in California. In the East it attacked the San Jose scale at 
the very outset, having' previously existed in this part of the country 
as a parasite of other species of Diaspinas. It was reared in this 
office from material collected at Riverside, Md., and Charlottesville, 
Va., and also from the material collected in the first orchards found 
infested, by Prof. J. B. Smith, of New Jersey. Professor Forbes has 
reared it in Illinois from the San Jose scale, and it has often been 
reared in Washington. That this insect has been steadily on the 
increase seems likely, but it is also probable that there is a certain 
periodicity in^its increase. In Bulletin No. 57 of the Maryland Agri- 
cultural Experiment Station, published in August, 1898, Prof. W. G. 
Johnson stated that he did not think it possible to secure anj^ imme- 
diate beneficial results from this parasite in the State of Maryland. 
He said that in all his efforts to secure them in his breeding cages he 
had been obliged to inclose hundreds of thousands of scales to obtain 
one parasite. Less than two years later, however," he stated that in a 
new locality for the San Jose scale, near Easton, Talbot County, Md., 
he found the parasites in enormous numbers. A quantity of small 
branches incrusted with the scale were brought to his laboratory and 
inclosed in breeding tubes. Much*to his surprise these tubes were 
swarming with parasites a few days later. From one tube 1,11-1 spec- 
imens of Aphelinus fuscipennis were taken, while a second tube gave 
432, a third 1,478, and a fourth more than 1,000. The other scale 
insects infested by this parasite are Aspidiotus rapax Comst., Aspidio- 
tus euonymi Targ., Lephdosap)lies gloverii Pack., and Lepidosaphes 
ulmi L. 

Aphelinus my tilaspidis he Baron is another important parasite which 
was reported in earlier publications as attacking the San Jose scale in 
California, where it was reared in Santa Clara County by Mr. E. M. 
Ehrhorn. It is also a common and widespread species, and infests, 
aside from the San Jose scale, Lepidosaphex ulmi, Chionaspis pinifolide 
Fitch, and Diaspis carueli Targ. In the East it is the commonest 
parasite of the 03^ster-shell scale of the apple. It has only recently 
been found to attack the San Jose scale, and it is an encouraging fea- 
ture that this and other eastern species have at last found a host satis- 
factory to themselves in Aspidiotus perniciosus. It was last year 
(1905) reared at this office from San Jose scale collected at Washington, 
D. C, by Mr. A. A. Girault, and at Youngstown, N. Y., by Mr. A. L. 
Quaintance. 

Aspidiotiphagus citrinus Howard (fig. 7) is one of the most impor- 
tant parasites of armored scales in California, to which State it was 
evidently imported from oriental regions. In California it has been 

« Bull. No. 26, new series, Division of Entomology, V. S. Dept. of Agr., pp. 73, 74. 



60 THE SAN JOSE OR CHINESE SCALE. 

repeatedly reared from the San Jose scale, but it is also known to 
attack Ohrysomphalus ficus Ashrn. and G. aurantii Mask, variety 
cltrinus Coq. It has made its way to the East and has been reared 
from the San Jose scale received from Hampton, Fla., where it was 
collected by Mr. A. L. Quaintance. This species seems to be found 
only in the warmer countries, and has not been found north of Florida 
in the East as yet. 

Anaphes gracilis Howard, which was reported in Bulletin No. 3 as 
originally reared from specimens collected at Riverside, Md., and 
later from twigs received from Charlottesville, Va., has not again 
been reared in this office from the San Jose scale, and the doubt 
exprest in our original note may be valid, namely, that this species 
may have been a parasite of some other scale insect, probably the 
oyster-shell scale, present on the twigs at the same time. The type 
of the species was reared from the oyster-shell scale of the apple, and 
it is quite likely to be an egg parasite only. 




Pig. 7. — Aspidiotiphagus citrinus, greatly enlarged (from Howard). 

The four species just mentioned were recorded in Bulletin No. 3. 
During the summer of 1905 three other species have been reared by 
Messrs. Quaintance and Girault. These are as follows: 

Physcus varicornis Howard was reared from material collected by 
Mr. Quaintance, May 30, 1905, at Hampton, Fla. There remains- a 
little doubt as to the parasitism of this species on pemiciosus, as 
according to the note there may possibly have been other hosts present. 
The known hosts of this species are Aspldiotus ancylus Putn., Chion- 
aspis quercus Comst. , and Chionaspis americana Johnson. 

Prospalta aurantii Howard (tig. 8) was reared from the San Jose 
scale July 31, 1905, from material collected from an infested pear tree 
on the grounds of the Department of Agriculture, at Washington. 
This parasite affects no less than nine distinct species of scale insects, 
and has been reared from material collected in California, Florida, 
District of Columbia, New York, New Mexico, and Illinois. 



TRUE PARASITES. 



61 



Ablerus clisiocampae, Ashm. (fig. 9) was reared in the summer of 
1905 b}^ Messrs. Quaintance and Giranlt from the San Jose scale 
occurring upon pear upon the Department grounds, at Washington. 




Fig. S.—Prospalta aurantii, greatly enlarged (from Howard). 

It was also reared from Diaspis pentagowi Targ., occurring upon 
the grounds of the Department. It affects also Chionaspis furfu rus 
Fitch, and is known to occur in North Carolina, in Illinois, and in the 
District of Columbia. 




p IG _ 9_ Ablerus clisiocampx, female, greatly enlarged (from Howard). 

Ehopoideus citrmus How. was reared in 1885 by Mr. Albert 
Koebele at Truckee, Nevada County, Cal., from Aspidiotus pernicio- 
sus on pear, and was described by the writer in the proceedings of the 
U. S. National Museum, No. 1112, October 1, 1898. This record was 



62 THE SAN JOSE OR CHINESE SCALE. 

overlooked in earlier publications from this Bureau, and the species, 
has not since been reared from any scale in any part of the country. 
The Koebele 1885 specimens are unique so far as known. 

PREDACEOTJS INSECT ENEMIES. 
NATIVE AND INTRODUCED ENEMIES OF OTHER SCALE-INSECTS. 

Practically all of the scale-feeding" Coccinellidse, or ladybirds, may 
feed on the larvae or older specimens of the San Jose scale. A dozen 
or more different species of ladybirds have been recorded in this coun- 
try as attacking this scale insect. Our most important native scale- 
feeding ladybird (Ohilocorus bivulnerus Muls.), commonly known as 
the twice-stabbed ladybird, and represented by one species or by a 
number of closety allied forms in different sections of the country, 
has not proven very efficient against the San Jose scale, at least in the 
East, altho commonly found in infested orchards. Its presence in 
eastern orchards, however, may often be accounted for b} r its being 
attracted by other native scale insects present in the same orchards. 
It is a slow breeder, having in the North at least but one brood 
annually, and seems to give very little promise of being of any great 
value as a means of controlling the San Jose scale in these sections of 
the United States. In California and elsewhere on the Pacific coast, 
but particularly in the Pacific coast region, the twice-stabbed ladybird 
is a much more active and important means in keeping the San Jose 
scale in check. It has been reported as multiplying enormously in 
infested orchards in California and almost effecting the extermination 
of this scale. Such a report was sent to us by Mr. N. W. Motheral 
relative to orchards in Tulare County, Cal." 

A large number of Coccinellidre imported by Mr. Koebele into Cali- 
fornia and colonized there have been reported as attacking the San 
Jose scale. The following species have been observed to have devel- 
oped this habit: Rhizobius debilis Black, Orcus australasise Boisd., 
Bhizobius lophanthse Blaisdell, Orcus chalybeus Boisd., and Micro- 
weisea b (Pentilia) misella Lee. The last named of these only is of any 
importance as a means of controlling the San Jose scale/ Another 

a See Insect Life, Vol. V, p. 53. 

b See Cockerell, Can. Entom.,Vol. XXXV, No. 2, p. 38, February, 1903. 

''The efficiency against scale insect pests of citrus trees ftf certain of Mr. Koebele's 
importations of foreign ladybirds into California led the State Horticultural Society 
of New Jersey to secure in 1896 from the State legislature an appropriation of $1,000 
for the purpose of importing into the State of New Jersey the natural enemies and 
parasites from other States and countries. Acting under this appropriation, Dr. 
John B. Smith, entomologist of the experiment station of New Jersey, visited Cali- 
fornia and sent a large quantity of several species of Australian ladybirds to various 
places in New Jersey, and some to Washington, D. C. Subsequent records of these 
importations indicated that they were all unsuccessful, and not a sign of the imported 
insects could be found in 1897. (See Report of Entomologist, New Jersey, 1897. ) 



ENEMIES OF OTHER SCALE-INSECTS. 



63 



and very interesting- species of Microweisea, recently described, also 
attacks the San Jose scale, and is referred to below. 

JRIiizobius lophcmthse was originally described from specimens found 
preying upon the San Jose scale at San Diego, Cal., but belongs to a 
lot which was introduced by Mr. Koebele on his first Australian trip 
(1888-89) and subsequently lost sight of, and was described by Doctor 
Blaisdell under the supposition that it was a new California species. 

Of our native predaceous insects attacking the San Jose scale, the 
most useful and interesting is the little coccinellid Microweisea rah Jin 
(fig. 10), which in both the larva and beetle state feeds upon this 
scale. It has a very wide range, occurring thruout the East and also 




Fig. 10.— Microweisea (Pentilia) misella: a, beetle; 6, larva; c, pupa, d, blossom end of pear, showing 
scales with larvse of Microweisea feeding on them, and pupa; of Microweisea attached within the 
calyx. All greatly enlarged (from Howard and Marlatt). 

in California, and began to attack the scale in numbers in the East in 
the first infested orchards discovered. This beetle was figured and 
its habits briefty indicated in Bulletin 3. The parent beetles prefer 
the full-grown female scales, and may frequently be observed stand- 
ing astride the scale, almost on end, pushing their heads under the 
margin of the protecting scale" to get at the soft, yellow insect 
beneath. The larva? of these beetles seem to feed more abundantly on 
the young scales. Their mode of attacking the older scales was not 
observed. The egg of this particularly useful coccinellid has not been 
found, but a favorite place for pupation was discovered within the 
calyx of the pears. This cavity is often literally filled with a mixture 
8449— No. 62—06 5 



64 THE SAN JOSE OR CHINESE SCALE. 

of young and old scale-insects, and frequently contains full-grown 
Pentilia larvae, their pupae, and freshly issued beetles. (See fig. 10.) 

This beetle was originally believed to be essentially an eastern species, 
and the fact that it attacked the San Jose scale so efficiently at the very 
outset was an interesting entomological experience, and led Doctor 
Howard to suggest its immediate introduction int) California, and one 
colony was sent, in 1894, to Professor Wood worth, at Berkeley. Our 
account of this useful beetle having come to the attention of Mr. J. E. 
Mclnt3>re, of Lespe, Cal., he urged us to procure for him some living 
specimens. Having already sent material to Mr. Woodworth, we were 
not immediately able to get a supply of the insects for a sending, but 
at this juncture we received from Mr. G. W. Harney, of Marysville, 
Cal., some beetles for determination, which proved to be Microweisea 
misella. He reported that in the mountainous regions of Yuba County 
many apple trees had been very badly infested with A. perniciosus, and 
that hundreds of these little ladybirds were found preying on the, scale. 
The occurrence of this ladybird in California as thus determined, and 
the fact that it there had the same useful habit, was a most interesting 
discovery. We immediately had Mr. Mclntyre's request transferred 
to Mr. Harney for attention. It is more than likely that this little 
beetle is airead}^ widely distributed over the Pacific slope, and it may 
prove to have a continental distribution instead of being restricted to 
the East, as original^ supposed. 

Another species of about the same size as Microweisea misella, but 
dark wine-red in color and representing a distinct species, has been 
under observation for some time by Mr. Frederick Maskew in south- 
ern California, and at the time of the writer's visit to California in the 
autumn of 1903 his attention was called to this scymnid, and some 
material was collected and submitted to Mr. E. A. Schwarz, who pro- 
nounced it to be an undescribed species. Mr. Maskew states that this 
little scymnid is always associated with the San Jose scale, and seems 
to be doing pretty good work against it. Mr. Schwarz has published 
a description of it under the name Pseudoweisea suturalis/ 1 

A small predaceous beetle, Collops quadrhnaculatus Fab., was 
observed by Mr. Schwarz at Charlottesville, Va. , feeding on the larvae 
of the San Jose scale. This beetle belongs t6 the family Malachiidae, 
concerning the life history and food habits of which A T eiw little is 
known. Evidentl} 7 these beetles are in part at least predaceous, as 
evidenced by this observation hy Mr. Schwarz. This beetle is, how- 
ever, not abundant enough apparently to have an}^ practical value as 
a means of controlling the San Jose scale. 

«Proc. Ent. Soc. Wash., Vol. VI, No. 2, April, 1904, pp. 118, 119 (issued May 21, 
1904). The name Pseudoweisea was used by mistake for Microweisea. — Ed. 



THE ASIATIC-LADYBIRD ENEMY OF THE SCALE. 65 

F 

THE ASIATIC-LADYBIRD ENEMY OF THE SAN JOSE SCALE. 

Thruout the region investigated in China and Japan (see pp. 11-15), 
wherever the San Jose scale occurred, apparently the chief natural 
agency in keeping it in check was a small ladybird, Chilocorus similis 
Rossi (figs. 11, 12, and PI. VII), which feeds upon the scale vora- 
ciously. This beetle is almost identical in appearance with the twice- 
stabbed ladybird of this country, Chilocorus Mvulnerus, in the adult 
stage, but in the larval stage differs from it distinctly in coloration. 







Fig. 11.— Asiatic ladybird (Chilocorus similis), oviposition and early larval stages: a, beetle in act of 
thrusting egg beneath scale; b, scale slightly raised, showing edge of egg beneath; e, scale lifted 
from bark, showing manner of attachment of egg to the inner surface; d, view of egg in the scale; 
e, egg magnified to show sculpturing; f, three eggs placed under flap of bark; g, same, natural size: 
h, i, dorsal and lateral views of newly hatched larva; j, larva, first stage, feeding on mature and 
young scales. All enlarged except g (author's illustration). 

The Asiatic species has a skin of a reddish or flesh tint, with black 
spines, while the general color of the larva of the native species is a 
dull gray, which, with black spines common to both, gives the latter a 
very much darker appearance. There are also certain minute struc- 
tural characters which can be made out only with the use of the 
microscope. There is, furthermore, a very distinct difference in the 
habits of the two species, the Asiatic ladybird going through an indefi- 
nite number of generations— four or five annually, depending upon 
the climate and latitude — and the American species having much fewer 



66 



THE SAN JOSE OR CHINESE SCALE. 



and often but a single generation annually. The slowness of breeding 
of the American species is a very great bar to its usefulness in the 
latitude which includes the principal deciduous-fruit interests of the 
United States. 

These facts were thoroly demonstrated from the breeding records 
of the material sent from China and Japan. Several sendings were 
made by the writer, but unfortunately most of the specimens died in 
transit or during the first winter. Two individuals, however, sur- 
vived, and during the first summer, that of 1902, from these two some 
5,000 or more beetles were secured. The breeding was first carried 






Fig. 12. — Asiatic ladybird (Chilocorus similis), later larval stages, pupa, and adult insect: a, second 
larval stage; b, cast skin of same; c, full-grown larva; d, method of pupation, the pupa being 
retained in split larval skin; e, newly emerged adult not yet colored; /, fully colored and perfect 
adult. All enlarged to the same scale (author's illustration). 

on in cages (PI. VIII), but afterwards the beetles were liberated, in the 
small experimental orchard attached to the insectaiy of the Bureau. 

A good many colonies were sent out to different States, both north 
and south, in the summer of 1902, many more in the summer of 1903, 
and a few additional colonies in 1904. Many of these colonies were 
liberated under rather unfavorable conditions, or, in other words, 
where there were very few infested trees, and the beetles probably 
became scattered and lost. The best success came with certain colo- 
nies sent to Georgia, and especially the notable case of the colony at 
Marshallville. This last was in an orchard containing some 17,000 



Bui. 62, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate VII. 




Pupating Larv/e of Chilocorus similis on the Terminals of Twigs in 
Department Orchard. (Author's Illustration. i 



Bui. 62, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate VIII. 




Cages Used in Breeding Asiatic Ladybird (Chilocorus similis> 
• Author's Illustration.i 



THE ASIATIC-LADYBIRD ENEMY OF THE SCALE. 67 

peach trees, covering about 75 acres, and adjoined a very much larger 
orchard belonging to the same owner, containing 250,000 trees. The 
ladybirds were liberated in August, 1902, in the smaller orchard. An 
examination of this orchard in July, 1903, indicated that the beetles 
were rapidly spreading, and that they would soon cover the smaller 
orchard. An estimate at this time of the number of ladybirds in all 
stages placed the total at somewhere between 25,000 and 40,000, and 
from observations breeding evidently continued at this point up to 
January. There was therefore in this latitude at least a very flatter- 
ing outlook for good results from the imported beetle. 

None of the colonies sent to northern States, that is, north of the 
District of Columbia, became established nor gave any useful results, 
and subsequent experience, and particularly the elaborate tests con- 
ducted by Dr. J. B. Smith, in New Jersey, would indicate that there 
is very little likelihood of usefulness from this beetle for northern 
fruit regions. That it may be established in the South was fully 
demonstrated by the experience noted in Georgia and b} T the experience 
in the orchard attached to the insectaiy of this Bureau, and in some 
other similar experiments where the results were perhaps less marked. 

At the time that this beetle began to demonstrate its probable con- 
siderable usefulness in Georgia and elsewhere in the South, the prac- 
tical value of the lime, sulfur, and salt wash became full}- established, 
and all commercial orchards were regularly subjected to spiking 
operations with this mixture. The result was that the scale food of 
the imported beetle was almost completely destroyed, and this was 
true in the principal orchards where it was doing its best work. As 
a consequence all of the beetles starved or their numbers were greatly 
reduced. 

The local stock of ladybirds in Washington practically disappeared 
with the gradual extermination of the scale food, and by the action of 
a native parasite which began to attack it after the first year. This 
parasite is one that we had previously reared from native ladybirds 
and had supposed it to be a secondary parasite; but the fact that it is 
a primarj^ parasite became fully demonstrated, and it attacked the 
Washington colony with such vigor as to practical^ exterminate it. 
Fortunately this same parasite does not seem to have been equally 
active in the case of the southern colonies, but it will undoubtedly 
always be a bar to great usefulness from this and allied ladybirds." 

A very serious difficulty in the introduction and establishment of a 
predaceous insect like this Asiatic ladybird beetle, which has rather 
limited powers of flight and is not carried about on nursery stock as 
are true parasites, is the ver}' scattering nature of infestation in this 
country. In spite of the fact that the San Jose scale has become so 

aSeeProc. Ent. Soc. Washington, Vol. V, No. 2, pp. 138, 139, 1903. 



68 THE SAN JOSE OR CHINESE SCALE. 

widely distributed and is doing so much damage to orchards, it is still 
far from being universally present, and occurs after all in a very scat- 
tering way in orchards here and there, with often 20 or 80 miles 
between places of infestation. In Japan and China, where the Chilo- 
corus occurs rather generally, it finds food for itself in every country 
and city dooryard, either the San Jose scale, or, in Japan particularly, 
the white peach scale (Diaepis pentagtona), on which it also feeds. 
The stock of ladybirds, therefore, is always kept up in greater or less 
numbers, ready to take hold of any unusual scale increase. In this 
country, if the local food supply is stopt by spraying operations or 
exhaustion, the ladybird necessarity dies, and very rarely will go far 
enough to find another infested orchard and a new food supply. Ulti- 
mately, when the San Jose scale occurs everywhere, predaceous lady- 
birds like the Asiatic species will undoubtedly become much more 
useful than they are under present conditions. 

Neither the Asiatic lad} T bird nor stnj other predaceous insect — and 
this is true also of the ch'alcidid parasites, tho perhaps in a less degree — 
can ever be expected to so thoroly exterminate the San Jose scale as 
to give sufficient protection for commercial orchard purposes, where 
absolutely clean or unspotted fruit is an essential. Predaceous and 
parasitic insects can only survive in connection with their host species,- 
and therefore ultimately there must be a natural balance which will 
fluctuate from year to year or period to period, in which alternately 
the parasite and the host insect get the upper hand, but both neces- 
sarily being continuously present. Where substantially clean fruit 
must be had, as for shipping and export purposes, spraying or some 
other direct means of control must be practised; and now that an 
inexpensive tree wash for the San Jose scale has been discovered, it 
is ver}^ much to the advantage of everyone to spray regularly, rather 
than trust to control by natural enemies. 

The importation of the Asiatic ladybird and the action of other pre- 
daceous enemies and of parasites can not, however, work anything but 
good. These feed upon or parasitize and destro}^ scale insects and 
will ultimately greatly reduce the virulence of the attacks of the San 
Jose species. The larva of the Asiatic ladybird was observed to eat 
the young of the San Jose scale at the rate of five or six insects to the 
minute, and even on an average of but one a minute a total of 1,440 
scale insects per day would be destroyed. The appetite of these larvas 
seems to be never satisfied, and they are eating practically all of the 
time. The adults also feed actively on the scale. In addition to their 
greater or less efficiency in generally checking the rapid multiplication 
of the San Jose scale, they and other natural enemies will ultimately 
be of special service in the control of the scale in private grounds and 
in small orchards and gardens the owners of which would not, under 
ordinary circumstances, practise regular spraying operations. 



FUNGOUS AND OTHER DISEASES. 69 

It is evident, from the records of true parasites given at the outset, 
that native parasites are beginning more and more to attack the San 
Jose scale. The native predaceous beetles will follow suit, and un- 
doubtedly as years go on the seriousness of San Jose scale infestation 
will diminish, as, in fact, it has already done in California and perhaps 
noticeably also already in some sections in the East. 

FUNGOUS AND OTHER DISEASES OF THE SAN JOSE SCALE. 

Scale insects are more or less subject to control b} T fungous and 
other diseases, and the San Jose species is no exception to this rule. 
Control by these agencies is particularly efficient in the moist Tropics, 
so much so that most scale insects are practically wanting in such 
regions. The armored scales, such as the San Jose scale, are rarely to 
be met with in tropical regions in any numbers, and where found are 
diseased in a large percentage of cases. The mealy bugs, however, 
are comparatively immune. The efficiency of these diseases as a means 
of control lessens as one leaves the Tropics, but in the subtropical 
regions of the United States, and even in the temperate regions, the San 
Jose scale has in man}^ instances been very general^ exterminated by 
disease. Several of these diseases are obscure and have never been 
scientifically studied, nor have thej^ developed any fruiting stage so 
that they could be studied with any degree of accuracy. 

In the early work with the San Jose scale in California, Mr. Coquillett 
reports the death of the San Jose scale from an unaccountable cause, 
supposedly disease, in Pasadena County, Cal., on pear trees which 
had not been treated with any kind of insecticide. Specimens of 
twigs covered with dead scales were submitted to the Bureau of 
Plant Industry for examination. No specific disease germ could be 
discovered, but this does not preclude the explanation of some definite 
disease as the cause of the death of the scales. . Similar cases have 
come up in the East several times, the first perhaps occurring at River- 
side, Md., in the earl} 7 history of the scale, where, without treatment, 
the scale died in a very large percentage thruout a considerable orchard. 
A number of similar cases were reported b}^ Doctor Howard in Bul- 
letin 12, one from Tifton, Ga., where a careful count of the scales 
showed that on one twig out of 183 scales 4 were living; on a second, 
out of 723 scales 2 were living, and on a third, out of 579 scales 28 
were living, giving 34 living scales out of 1,485, a mortality rate of 
97.7 per cent. A similar case was reported also from Wadley, Ga., 
by Professor Starnes, and Professor Alwood has noted the same con- 
ditions at Vienna, Va. Doctor Howard also records the fungus- 
infested scale reported by Doctor Fletcher at Fruitland, Ontario, altho 
here the fungus or disease is probably a different one. 

A more promising and important disease of the San Jose scale is 
the cosmopolitan scale-insect parasitic fungus Sphxrostllba poccqphila, 



70 THE SAN JOSE OR CHINESE SCALE. 

which Professor Rolfs, of the Florida experiment station, identified 
and discust at length in Bulletin 41 of that station, published in 
1897. This disease is common to other species of scale insects, is 
widely distributed in Florida and elsewhere in the Southern States, 
and was found to attack the San Jose scale in Florida very efficiently. 

As outlined by Professor Rolfs, a San Jose scale attacked by this 
fungus is usually transformed into a mass of mycelia before there is 
any external appearance of change. When the body of the insect has 
been consumed a bright, orange-colored protuberance forms at the 
base of the scale, or at times it breaks thru the protecting cover of the 
insect. This orange-colored protuberance is the most conspicuous 
part of the fungus and the only portion visible to the unaided e3^e. 
It varies in size from an eighth to a fortieth of an inch. Those that 
average about one-sixteenth of an inch are most abundant under favor- 
able conditions. These protuberances are the spore-bearing bodies, 
and contain spores in great numbers. These orange-colored spore- 
bearing bodies are developed and mature within six weeks from the 
time of infection, and countless numbers of spores are liberated from 
them during rains and are washed down the trees and sometimes to 
the ground. Other and smaller spore bodies are eventually produced 
from the germination of these, and are carried about by the air or 
other means, and thus extend the infection. The biolog}^ of this 
fungus is rather technical and complicated, and need not be gone into 
in detail/' 

Professor Rolfs demonstrated experimentally that this fungus could 
be transferred from tree to tree artificiall}^. His process was to inocu- 
late acid bread with pure cultures of the fungus, and three weeks later 
to break up a piece of bread about an inch square in cold water, and 
apply to a scaly tree by means of a sponge or cloth or by spraying. 
The applications were made in midsummer, and the observations as to 
results late in February. Out of eight experiments four were success- 
ful, three unsuccessful, and one doubtful, the tree having in the mean- 
time died. A good deal of interest was aroused by this publication 
of Professor Rolfs's, and experiments with this fungus were made in 
Georgia and by entomologists to whom cultures were distributed in 
the North and West. The results from these experiments in the more 
northern regions were not, as a rule, very satisfactoiy, and the fun- 
gus has not demonstrated great practical merit outside of Florida and 
perhaps southern Georgia. Undoubtedly, however, it is a very .valu- 
able aid in the control of the San Jose scale thruout the Gulf region, 
where high temperatures associated with sufficient humidity occur. 

The most careful experimental work with this fungus was that con- 
ducted by Prof. J. B. Smith in New Jersey. While nearly all the 

« See Bui. No. 41, Florida Agric. Exp. Sta., 1897. 



FUNGOUS AND OTHER DISEASES. 7l 

experiments made b} r Doctor Smith were barren of results, one yielded 
rather notable success. This was in the orchard of Mr. Horace 
Roberts, at Fellowship, N. J. Twigs from Florida bearing San Jose 
scales infested by the fungus were tied to branches of infested trees 
about the middle of June. Toward the end of September Doctor 
Smith found the fungus upon almost all of the trees upon which twigs 
had been tied. He reports that it had spread pretty well over the 
trees, and in some cases its presence was obvious from the surface of 
the ground to the extremity of the branches, hundreds of patches of 
the orange fruiting processes being everywhere noticeable. In no 
case, however, so far as Doctor Smith observed, had the disease spread 
to an}^ adjacent trees, unless in a less visible stage, and by no means 
all of the scales on the trees containing these twigs were dead. 

Various saprophytic fungi which develop in diseased or dying wood 
are sometimes so closety associated with the scale, or in fact grow on 
the scale as well as on the wood, that the inference is a very natural 
one that the scale is being killed by these fungi. Examples of two 
such fungi have recentty been sent to us for examination and were 
submitted to the Laboratory of Plant Patholog} r of this Department 
for investigation. The following report indicates their nature: 

We find two species of fungi present upon these specimens. The most conspicuous 
form is Micropera cotoneaslri (Fr. ) Sacc. The fungus forms small, black, somewhat 
pulvinate masses on the surface of the bark, sometimes covering old scales. The 
plant is not mature and shows in only a few instances pycnospores. It is not an 
uncommon fungus upon diseased or dying branches of fruit trees and other closely 
related rosaceous plants. Its relation to the scales present is probably always acci- 
dental. The fungus probably develops more readily upon the twigs which have 
been injured or partially killed by the scale. 

There is also another fungus present in a considerable quantity on some of the 
twigs. It consists of minute black, slender stipitate bodies a few millimeters high. 
This is also immature, showing only conidia. It is probably Spinctrina cerasi B. & C. 
In the absence of the ascigerous form of the fungus it is impossible to state positively 
that this is the species. As in the case of the other fungus mentioned, it probably 
bears no parasitic relation to the scales present, as it usually occurs on dead or dying 
branches of fruit trees. 

The first fungus mentioned (Micropera) is the one most closely associated with the 
scales. 

The plan of using contagious insect diseases to destroj^ important 
pests, such as the San Jose scale, is a very attractive one, and in the 
case of the San Jose scale well worthy of more careful stud} T than has 
so far been given it. It is possible that some of the obscure forms of dis- 
ease which have already appeared in northern districts, as in Maryland, 
Virginia, and in the State of Washington, may be capable of artificial 
propagation and distribution, and yield results of distinct value in the 
control of the scale. All of these fungous and other diseases will 
undoubtedly become more efficient with the more wide and general 
distribution of the scale. 



72 THE SAN JOSE OR CHINESE SCALE. 

MEANS OF CONTROLLING THE SAN JOSE SCALE. 
INSECTICIDE APPLICATIONS. 

Active experimentation with different remedies for the San Jose 
scale was instituted by this Office promptly after the discover}- of the 
occurrence of this pest in eastern orchards and nurseries. A full 
record of these early experiments is given in Bulletin No. 3 (new 
series) of this Bureau, pages 56 to 71. The subject of these experi- 
ments will not be gone into iti detail. They covered the use of the 
lime-sulfur washes employed against the San Jose scale in California, 
the hydrocyanic-acid-gas treatment for orchards and nursery stock, 
lye washes, pure kerosene, kerosene-soap emulsions, resin washes, and 
soap washes. The early experience with the lime, sulfur, and salt 
wash was unfavorable, largely due apparently to the fact -that the 
observations on the trees treated were not continued long enough to 
note the effect of the late summer results. Good results were 
obtained with the kerosene emulsions, and particularly with the soap 
washes, and the lish-oil-soap wash became one of the standard means 
of controlling the scale and is still among the best and safest washes 
to be used, altho rather more expensive than necessary, except where 
only a few trees are to be treated. 

The subject of remedies was promptly taken up by different experi- 
ment station entomologists in the East, and a vast body of experimen- 
tal data is now on record in various station publications. The study 
of the subject of remedies has also been continued by this Bureau and 
reported in different bulletins. The lime, sulfur, and salt wash at 
first reported on adversely by us was afterwards demonstrated to be 
of real value, and experimental work was taken up, first by the Illinois 
Experiment Station, under Professor Forbes, and subsequently by other 
stations, and it has now come to be the generally accepted remedy for 
the San Jose scale. Without going at all in detail into the subject 
historically, it is sufficient for the purpose of this bulletin to reproduce 
the recommendations for the control of the San Jose scale substantially 
as given in the fourth revised edition of our Circular 42. 

In addition to the standard remedies mentioned below a great many 
proprietary substances have appeared, and some of these have some 
merit. The best of these are certain merchantable brands of lime- 
sulfur compounds, and oils which have been treated by some secret 
process to render them miscible in water. The predominating con- 
stituent of the latter is mineral oil, and the resulting mixture, which 
is not apparently an emulsion, is undoubtedly of value if used in suf- 
ficient strength to get the required amount of oil on the trees. There 
is no advantage in using an} 7 of these compounds over the standard 
insecticides, and their greater cost is a distinct objection, together 



THE LIME-SULFUR WASH. 73 

with the uncertainty of composition. Nevertheless, where only a few 
trees are to be sprayed and the owners would probably not go to the 
trouble of preparing a standard emulsion or the lime-sulfur wash, the 
use of miscible oils or ready-made lime-sulfur washes is a good deal 
better than nothing, and may give very good results. Space does not 
permit the mention and discussion of a number of other mixtures which 
have not proven satisfactory nor the equal of standard means of 
control. Some of these have been experimented with somewhat 
extensively by different experiment station entomologists. 

The methods of control which have been especially followed in the 
Eastern States are (1) the lime-sulfur wash, (2) the soap treatment, 
(3) treatment with pure kerosene, (1) treatment with crude petroleum, 
(5) treatment with mechanical mixtures of either of the last two oils 
with water, and (6) petroleum emulsion with soap. All of these 
methods have proved themselves to be successful against the San Jose 
scale when properly carried out. As compared with the lime-sulfur 
wash, the others mentioned are more expensive, and the two oils, 
unless very carefully applied, are likely to injure the treated plants 
and are now seldom used. One's choice of method must therefore be 
governed by availability, special needs, and experience. In the maiu 
these remedies, including the lime-sulfur wash, are winter treatments 
and ma3 r be emploj^ed at any time when the trees are in dormant, leaf- 
less condition. The weaker oil-water mixtures and the emulsions may, 
however, be used in the growing season. The treatments enumerated 
are all for trees in the orchard. Nursery stock badly enough infested 
to require such treatment is best destroyed. For the general disinfec- 
tion of nursery stock the hydrocyanic-acid-gas treatment is the standard 
and only satisfactory means. 

THE LIME-SULFUR WASH. 

In .California, where this scale insect first occurred, the standard 
remedy for it is the lime, sulfur, and salt wash, a mixture formerly 
used as a sheep dip in Australia and employed with little change against 
the San Jose scale, and by a lucky chance proving effective. This 
wash was naturally first thought of on the discovery of the San Jose 
scale in eastern orchards. The earlier tests, however, conducted Irv 
this office in 1894, were unfavorable, and the experimentation which 
followed resulted in the demonstration by ourselves and others of sev- 
eral distinct and valuable methods of control noted below. Later 
studies of the action of this wash in California led the writer in 1900 
to give it a further careful trial in the East, with most successful 
results, demonstrating that with favoring conditions, i. e.. absence of 
clashing rains for a few days subsequent to the application, it would 
give just as good results in the Eastern States as on the Pacific coast. 



74 . ' THE SAN JOSE OR CHINESE SCALE. 

A year later (1901-2) very elaborate tests conducted by Doctor Forbes 
in Illinois showed that fairly hard rains will not always invalidate 
spraying with this mixture. A vast amount of experience of the most 
practical kind since gained, contributed to by all the eastern experi- 
ment stations- and by the big commercial fruit growers of the Middle 
and Eastern States, has fully demonstrated the practical merit of this 
wash and its superiority to others in point of safety to trees and in 
cheapness. The wash is furthermore a valuable fungicide and is nota- 
bly useful against the peach leaf curl, sprayed trees being practically 
immune from this disease, so that the cost of treatment is often more 
than made good by the fungicidal benefit alone. Its disadvantages are 
the difficult}^ of preparation and the heavy wear which it entails on 
apparatus — objections, however, which do not offset its notable advan- 
tages, particularly for commercial orchard work or where the number 
of trees to be treated is sufficient to warrant the trouble of its prepara- 
tion . It is, in fact, the standard spray now used in commercial orchards 
for the San Jose scale. 

In the matter of composition of the wash scarcely any two experi- 
menters agree. Salt was a part of the original composition of the sheep 
dip and has long been retained, with the idea that it added, perhaps, to 
the caustic qualities, and particularly to the adhesive nature of the 
wash. For the latter purpose a very small amount only, 1 or 2 pounds 
to the bushel of lime, need be added, following the custom in the 
preparation of whitewash mixtures. In practical experience, however, 
the salt seems to have been of very little benefit and is therefore 
omitted in the formula now given. The proportion of lime and sulfur 
is a matter of some indifference. The mixture obtained is sulphide of 
lime, and if an excess of lime is used it simply remains undissolved in 
the mixture and adds to the whitewashing character of the application. 
Too much lime is distinctly objectionable, however, because of the 
greater difficulty of spraying and harder wear on the pump and nozzles. 
The formula here given is substantially the one which has been hith- 
erto recommended by this Bureau, reduced to the 45 or 50 gallon basis, 
or the capacit}^ of the ordinary kerosene barrel commonly used in its 
preparation by the steam method. 

Unslaked lime pounds. . 20 

Flowers (or flour) of sulfur do 15 

Water to make : gallons. . 45 to 50 

The flour of sulfur, although requiring somewhat longer cooking, 
seems to make as good a wash as the flowers of sulfur, but an hour of 
thoro cooking is ample for either. Good qualit}^ stone lime should be 
secured and slaked in a small quantity of hot water in the cooking 
vessel, say one-third the full dilution. The sulfur, previously mixt 
up into a stiff paste, should be added at once to the slaking lime. The 



Bui. 62, Bureau of Entomology, U. S. Dept of Agriculture. 



Plate IX. 




Steam Plants for Cooking Lime-Sulfur Wash. 
I From Quaintance. i 



THE SOAP TREATMENT. 75 

whole mixture should be boiled for at least one hour, either in an iron 
kettle over a fire out of doors or in barrels by steam (see PI. IX). 
Prolonged boiling increases the percentage of the higher sulphides. 
but the practical end is obtained with a boiling of the time indicated. 
In the process of making, the color changes from yellow to the clear 
brown of sulphide of lime, except for the excess of lime floating in it. 
After an hour's boiling the full quantity of cold water can be added, 
and the mixture should then be promptly applied in order to get its 
full strength before the higher sulphides are lost by cooling and 
crystallizing out. In transferring to the spra}" tank it should be 
past thru an iron screen or strainer, and the tank itself should be pro- 
vided with an effective agitator. 

The wash is a winter application and can not be applied to trees in 
leaf. It may be applied at any time after the falling of foliage in 
early winter and prior to the swelling of the buds in spring. It will 
probably be necessary also to make this application every 3*ear, or at 
least as often as the San Jose scale develops in any numbers. The 
wash kills the San Jose scale not only by direct caustic action, but 
apparently also by reason of the coating on the trees, which remains 
in evidence until midsummer or later, and may kill or prevent the set- 
tling of any young scale insects which may come from parents escaping 
the winter action. 

Two applications may be given badly infested orchards — one in late 
fall, the other in late spring. Where but one application is given, the 
late spring just before the buds open is the best time. 

The wear on pumps and nozzles can be kept to a minimum by care- 
fully washing the apparatus prompt^ after use. The Vermorel nozzle 
is the best one for the wash, and additional caps may be secured to 
replace worn ones. The use of an air or other gas pressure pump 
instead of the ordinary liquid pump will save the wear of the lime on 
the pump. In spra} T ing with this wash clothing is ruined, and only 
the oldest garments should be worn. Care should be taken also to 
protect the eyes to avoid unnecessary inflammation. 

THE SOAP TREATMENT. 

Whale-oil or fish-oil soap, preferabl}' made with potash lye. is dis- 
solved in water by boiling at the rate of 2 pounds of soap to the gallon 
of water. If applied hot and on a comparatively warm da}' in winter, 
it can be easil} T put on trees with an ordinary spray pump. On a very 
cold day, or with a cold solution, the mixture will clog the pump, and 
difficulty will be experienced in getting it on the trees. Trees should 
be thoroly coated with this soap wash. Pear trees and apple trees 
may be sprayed at any time during the winter. Peach trees and plum 
trees are best sprayed in the spring, shortly before the buds swell. 



76 THE SAN JOSE OR CHINESE SCALE. 

If sprayed in midwinter or earlier, the soap solution seems to prevent 
the development of the fruit buds, and a loss of fruit for one year 
is apt to be experienced, the trees leafing* out and growing-, however, 
perhaps more vigorously on this account. The soap treatment is per- 
fectly safe for all kinds of trees and is very effective against the scale. 
With large trees or badly infested trees, preliminary to treatment it 
is desirable, with this as well as other applications, to prune them 
back very rigorously. This results in an economy of spray and makes 
much more thoro and effective work possible. The soap can be secured 
in large quantities at from 3i cents to 4 cents a pound, making the 
mixture cost, as applied to the trees, from 7 cents to 8 cents a gallon. 
The success of the soap treatment is largely influenced by the quality 
of the soap used. Maiw brands are on the market, mostly made with 
soda lye. A potash soap should be insisted on, and one that does not 
contain more than 30 per cent of water. The soda soap washes are 
apt to be gelatinous when cold and difficult or impossible to spraj T 
except when kept at a very high temperature. 

KEROSENE TREATMENT. 

This consists in spraying the trees with ordinary illuminating oil 
(coal oil or kerosene). The application is made at an}^ time during the 
winter, preferably in the latter part, and by means of a spray pump 
making a fine mist spraj^. The application should be made with the 
greatest care, merely enough spray being put on the plant to moisten 
the trunk and branches without causing the oil to flow down the trunk 
and collect about the base. With the use of this substance it must be 
constantly borne in mind that careless or excessive application of the 
oil will be very apt to kill the treated plant. The application should 
be made on a bright, dry day, so that the oil will evaporate as quickly 
as possible. On a moist, cloudy day the evaporation is slow, and 
injury to the plant is more apt to result. If the kerosene treatment 
be adopted, therefore, it must be with a full appreciation of the fact 
that the death of the tree may follow. This oil has been used, how- 
ever, a great many times and very extensively without consequent 
injury of any kind. On the other hand, its careless use has frequently 
killed valuable trees. Its advantages are its effectiveness, its avail- 
ability, and its cheapness, kerosene spreading very rapidly and much 
less of it being required to wet the tree than of a soap and water spray. 
Pure kerosene is more apt to be injurious to peach and plum than to 
pear and apple trees, and the treatment of the former, as with the 
soap wash, should be deferred until spring,'just before the buds swell. 
With young trees especiall} 7 it is well to mound up about the trunk a 
few inches of earth to catch the overflow of oil, removing the oil- 
soaked earth immediately after treatment. 



THE OIL- WATER TREATMENT. 77 

THE CRUDE-PETROLEUM TREATMENT. 

Crude petroleum is used in exactly the same way as is the common 
illuminating - oil referred to above. Its advantage over kerosene is 
that, as it contains a very large percentage of the heavy oils, it does 
not penetrate the bark so readily, and, on the other hand, only the 
light oils evaporate, leaving" a coating of the heavy oils on the bark, 
which remains in evidence for months and prevents any young scale 
which may come from the chance individuals that were not reached 
bj r the spray from getting a foothold. Crude .petroleum comes in a 
great many different forms, depending upon the locality, the grade 
successfully experimented with in the work of this Bureau showing 
43° Baume. Crude oil showing a lower Baume than 43° is unsafe, 
and more than 45° is unnecessarily high. The lower specific gravity 
indicated (43°) is substantially that of the refined product, the removal 
of the lighter oils in refining practically offsetting the removal of the 
paraffin and vaseline. The same cautions and warnings appty to the 
crude as to the refined oil. 

THE OIL-WATER TREATMENT. 

Various pump manufacturers have now placed on the market spray- 
ing machines which mechanically mix kerosene or crude petroleum 
with water in the act of spraying. The attempt is to regulate the 
proportion of kerosene so that any desired percentage of oil can be 
thrown out with the water and be broken up b} 7 the nozzle into a sort 
of emulsion. Some of these machines, when eveiwthing is in good 
working order, give fairty satisfactory results, but absolute relia- 
bility is far from assured. 

The best outlook for good apparatus of this sort seems to be in car- 
rying the oil and water in separate lines of hose to the nozzle, uniting 
them in the latter, and in maintaining an absolute equality of pressure 
on both the oil and the water tanks b} T employing compressed air as 
the motive force, kept up by an air pump, the air chamber communi- 
cating with both of the liquid receptacles. An} T other source of con- 
stant pressure, as carbonic acid gas or steam, will answer. One or 
more manufacturers are now working on apparatus of this general 
description. A 10-per-cent strength kerosene can be used for a sum- 
mer spray on trees where the San Jose scale is multiplying rapidly and 
where it is not desirable to let it go unchecked until the time for the 
winter treatment. The. winter treatment with the water-kerosene 
sprays may be made at a strength of 20 per cent of the oil. Appli- 
cations of the oil-water spray should be attended with the same pre- 
cautions as with the pure oil, and there is even somewhat greater risk, 
owing- to the natural tendency one has to apply the dilute mixture 
much more freely than the pure oil. The application should be merely 



78 THE SAN JOSE OR CHINESE SCALE. 

enough to wet the bark, and should not, to any extent, at least, run 
down the trunk. The collection of water and oil about the trunk is 
just as dangerous to the tree as is that of the pure oil. 

In the use of the oil sprays noted above one who has not had expe- 
rience with them is advised to make some careful preliminary tests to 
fully master the process, preferabty waiting two or three weeks to 
determine the results before entering on the general treatment of the 
orchard. It is well, also, with the oil- water mixtures, to test the pump 
from time to time,. spraying into a glass jar or bottle to determine by 
actual measurement whether the correct percentages of oil and water 
are being' maintained. 

PETROLEUM-SOAP EMULSIONS. 

The kerosene-soap emulsion, following chiefby the Riley-Hubbard 
formula, has been one of the standard means against scale insects for 
twenty years. The distillate emulsion generally emploj^ed in Cali- 
fornia for spraying citrus trees, on which the lime, sulfur, and salt 
wash can not be used, is substantially the same thing, except that it 
is made with the California distillate or petroleum oil. Crude petro- 
leum of any kind, as well as the refined product, may also be used in 
making this emulsion. The use of the soap emulsions against the San 
Jose scale in the East has not been veiy general, on account of the 
greater facility with which the pure oil or oil-water mixtures can be 
applied. The difficulty of obtaining uniform results with the latter 
has led to a return to the use of emulsions to some extent, and there 
can be no doubt about their superior merit when it is desired to dilute 
the pure oils. Emulsions may be applied at any strength with abso- 
lute confidence that there will be no variation. Where the emulsion 
can be prepared wholesale by steam power its employment is attended 
with no difficulties. In California it is prepared by oil companies and 
sold at very slightly more than the cost of the oil and soap ingredi- 
ents. It is made after the following formula: 

Petroleum . gallons. . 2 

Whale-oil soap (or 1 quart soft soap) . pound. . i 

Water (soft) gallon. . 1 

The soap, first finety divided, is dissolved in the water by boiling and 
immediately added boiling hot, a,wa,j from the tire, to the oil. The 
whole mixture is then agitated violently while hot by being pumped 
back upon itself with a force pump and direct-discharge nozzle throw- 
ing a strong stream, preferably one-eighth inch in diameter. After 
from three to five minutes' pumping the emulsion should be perfect, 
and the mixture will have increased from one-third to one-half in 
bulk and assumed the consistency of cream. Well made, the emulsion 
will keep indefinite^ and should be diluted only as wanted for use. 



FUMIGATION OF NTJESEEY STOCK. 79 

In limestone regions, or where the water is very hard, some of the 
soap will combine with the lime or magnesia in the water, and more or 
less of the oil will be freed, especially when the emulsion is diluted. 
Before use such water should be broken with lye, or rain water 
should be employed. 

For winter sprays dilute the emulsion with either 3, 1, or 5 parts of 
water, giving a percentage of oil of approximately 17, 13, and 11 per 
cent. The strength in oil of this application on trees as compared with 
the oil-water sprays is the equivalent of 25, 20, and 15 per cent oil, 
because relatively more of the heavier oil-soap emulsion is held by the 
bark. The two stronger mixtures may be used on the apple and pear 
and the weaker one on peach and plum. 

For summer applications dilute with 7, 10, or 15 parts of water, giv- 
ing approximately 8, 6, and 1 per cent of oil. The weaker strengths 
nniv be used on trees with tender foliage, such as that of peach, and the 
greater strength for strong foliage plants, like the apple and pear. 

FUMIGATION OF NURSERY STOCK. 

All nursery stock which is under the least suspicion of contamination 
with the San Jose scale should be fumigated; and it is perhaps worth 
while to fumigate in any case to give the utmost assurance of safety 
to the purchaser. The hydrocj^anic-acid-gas fumigation is the one to 
use. This gas is generated by combining potassium cyanide, sulfuric 
acid, and water. The proportions of the chemicals are as follows: 
Refined potassium cyanide (98 per cent), 1 ounce; commercial sulfuric 
acid, 1 ounce; water, 3 fluid ounces — to every 100 cubic feet of space 
in the fumigating room or house. The latter should be as nearly air- 
tight as possible and provided with means of ventilation above and at 
the side, operated from without, so that at the end of the treatment 
the poisonous gases can be allowed to escape without the necessit}^ of 
airyone entering the chamber. The generator of the gas may be any 
glazed earthenware vessel of 1 or 2 gallons capacit} 7 , and should be 
placed on the floor of the fumigating room and the water and acid 
necessary to generate the gas added to it. The cyanide should be 
added last, preferabty in lumps the size of a walnut. Promptly after 
adding the cyanide the room should be vacated and the door made 
fast. The treatment should continue forty minutes. It must be borne 
in mind that the gas is extremely poisonous and must under no circum- 
stances be inhaled. The gas treatment is effective against the scale on 
growing trees in the orchard also; but the difficulty and expense of 
the treatment, except for nursery stock, make it prohibitive in the case 
of deciduous fruits. 

8449— No. 62—06 6 



80 THE SAN JOSE OR CHINESE SCALE. 

LEGISLATION AGAINST THE SAN JOSE SCALE. 

As indicated in another place, no insect has been the subject of so 
much domestic and foreign legislation as has the San Jose scale. In 
this countiy nearly all the States have past laws regulating the sale 
and shipment of nursery stock and providing for inspection on account 
of this scale insect, and a great many foreign countries have made 
regulations regarding the importation of American plants and fruits. 

The domestic legislation on insect matters, including the San Jose 
scale, was compiled by Doctor Howard and published as Bulletin No. 
13 (new series) of this Office in 1898, and the foreign legislation up 
to 1900 is summarized by Doctor Howard in Circular No. 11 of this 
Office, published in August, 1900. There has been a great deal of 
additional legislation by different States subsequent to the publication 
of Bulletin No. 13, and b}^ a resolution of the Association of Economic 
Entomologists and the American Association of Horticultural Inspect- 
ors this Office has collected, by the aid of special committees appointed 
by the two associations mentioned, all of the laws in their present 
form, and these have veiy recently been published as Bulletin No. 61 
of the Bureau of Entomology. There have been also some charges 
in foreign legislation, and ultimatel3 r a revision of Circular 41 will be 
issued. The subject is much too large and bulky to be considered in 
this bulletin. 



INDEX 



Ablerus clisiocampse, scale hosts 58, 61 

Acacia, food plant of San Jose scale 36 

Acer platanoides, food plant of San Jose scale 38 

saccharinum, food plant of San Jose scale 38 

sp. , food plant of San Jose scale . . 38 

Actinidia arguta, food plant of San Jose scale 38 

polygama. (See Actinidia arguta.) 

JEsculus hippocastanum, food plant of San Jose scale 38 

Akebia quinata, food plant of San Jose scale 36 

sp. , food plant of San Jose scale 36 

Alder. (See Alnus sp. ) 

Almond. (See Primus amygdalus and P. japonica.) 

Alii us sp. , food plant of San Jose scale ". 38 

Althea, shrubby. (See Hibiscus syriacus.) 

Amelanchier canadensis and spp. , food plants of San Jose scale 36 

Ampelopsis quinquefolia, food plant of San Jose scale 38 

Anaphes gracilis, is it parasite of San Jose scale? 58, 60 

Ants, spreading San Jose scale 57 

Aonidiella eucalypti, not variety of Aspidiotus perniciosus 55 

Aphelinus fuscipennis, scale hosts 58-59 

mytilaspidis, scale hosts 58, 59 

Apple. (See Pyr us mains.) 

haw, food plant of San Jose scale 14 

Apricot. (See Prunus armeniaca.) 
Arborvitae. (See Thuya occidentalis.) 
Aronia nigra. (See Sorbus melanocarpa.) 
Ash. (See Fraxinus sp. arM F. americana. ) 

mountain. (See Sorbus sp., S. americana, and S. aucuparia.) 

Aspidiotiphagus citrinus, scale hosts 58, 59-60 

Aspidiotus ancylus, parasitized by Physcus raricornis 60 

euonymi, parasitized by Aphelinus fuscipennis 59 

fusca = Aspidiotus perniciosus 55 

perniciosus. (See also Scale, San Jose.) 

Aspidiotus fusca a synonym 55 

var. albopunctatus = Aspidiotus perniciosus 55 

andromelas = Aspidiotus perniciosus 55 

eucalypti — Aonidiella eucalypti 55 

rapax, parasitized by Aphelinus fuscipennis 59 

Basswood. (See Tilia sp. and T. americana. ) 

Beech, purple-leaved. (See Fagus sylvatica var. purpurea.) 

Betula alba, food plant of San Jose scale 38 

sp. , food plant of San Jose scale 38 

Birch. (See Betula sp. and B. alba.) 

SI 



82 INDEX. 

Page. 

Birds, spreading San Jose scale .• „„•„„„„.„„...... 57 

Blackberry, common. (See Rubus nigrobaccus.) 
Box. (See Buxus.) 

Buxus, food plant of San Jose scale - 38 

C&stanea americana, food plant of San Jose scale 38 

Catalpa bignonoides, food plant of San Jose scale 38 

common. (See Catalpa bignonoides. ) 

sp., food plant of San Jose scale 38 

Ceanothus americanus, food plant of San Jose scale 38 

Celtis occidentals, food plant of San Jose scale 38 

Cercidiphyllum japonicum, food plant of San Jose scale 38 

Cherry. (See Primus avium, P. cerasus, and P. pumila var. besseyi.) 
Chestnut. (See Castanea americana.) 

Chilocorus bivulnerus, comparison with Chilocorus sirnilis 65-66 

enemy of San Jose scale 62 

sirnilis. (See also Ladybird, Asiatic). 

comparison with Chilocorus bivulnerus 65-66 

Chinese scale. (See Scale, San Jose, and Aspidiotus perniciosus. ) 

Chionaspis americana, parasitized by Physcus varicornis _ 60 

furfurus, parasitized by Ablerus clisiocampse 61 

pinifolise, parasitized by Aphelinus mytila.spidis 59 

quercus, parasitized by Physcus varicornis 60 

Chokeberry, black. (See Sorbus melanocarpa. ) 
Chokecherry. (See Primus virginiana.) 

Chrysomphalus aurantii var. citrinus, parasitized by Aspidiotiphagus citrinus 60 

ficus, parasitized by Aspidiotiphagus citrinus 60 

Citrus aurantium. (See also Orange, and Citrus fruits.) 

food plant of San Jose scale 38, 41 

fruits and San Jose scale - 42-43 

trifoliata, food plant of San Jose scale 36, 41 

Climate, affecting spread of San Jose scale 33-34 

Collops quadrimaculatus, enemy of San Jose scale ._. 64 

Color protection, of San Jose scale 57 

Cornus alba var. sibirica, food plant of San Jose scale 36 

alternifolia, food plant of San Jose scale 38 

amomum, food plant of San Jose scale .*. 39 

baileyi, food plant of San Jose scale ." 36 

candidissima., food plant of San Jose scale - 39 

circinata, food plant of San Jose scale 39 

florida, food plant of San Jose scale 39 

sanguinea, food plant of San Jose scale 36 

stolonifera, food plant of San Jose scale h — 38 

Cotoneaster sp., food plant of San Jose scale 36, 42 

vulgaris, food plant of San Jose scale 36 

Crab apple. (See Pyrus sp. ) 

Cratsegus coccinea, food plant of San Jose scale - 37 

cordata, food plant of San Jose scale 37 

crus-galli, food plant of San Jose scale 37 

oxyacantha, food plant of San Jose scale 42 

sp. , food plant of San Jose scale 37 

Currant. (See Ribes rubrum, R. nigrum, and R. aureum.) 

Cydonia japonica, food plant of San Jose scale 37 

vulgaris, food plant of San Jose scale : 37 



INDEX. 83 

Page. 

Deutzia sp., food plant of San Jose scale 39 

Dewberry. ( See Rubus villosus. ) 

Diaspis carueli, parasitized by Aphelinus mytilaspidis 59 

pentagona, Asiatic ladybird an enemy 68 

parasitized by Ablerus clisiocampx 61 

Diospyros virginiana, food plant of San Jose scale 39 

Diseases, of San Jose scale, artificial spread 70-71 

Distillate emulsion. (See Petroleum-soap emulsions.) 

Distribution of San Jose scale affected by climate 33-34 

means 56-58 

Dogwood, red flowering. (See Cornus florida.) 

Elseagnus longipes, food plant of San Jose scale 39 

sp. , food plant of San Jose scale 39 

Elder. ( See Sambucus sp. ) 

Elm. (See Ulmus sp., U. americana, and U. campestris.) 

Entomosporium maculatum, resemblance to San Jose scale 35 

Eucalyptus sp. , food plant of San Jose scale 39 

Euonymu§ sp. , food plant of San Jose scale 39 

Fagus sylvatica var. purpurea, food plant of San Jose scale 37 

Ficus carica, food plant of San Jose scale 39 

Fig. (See- Ficus carica.) 

Forsythia sp., food plant of San Jose scale 39 

Fraxinus americana, food plant of San Jose scale 39 

sp. , food plant of San Jose scale 39 

Formica schaufussi, not carrying San Jose scale 57 

Fumago salicina, on San Jose scales 51 

Fumigation of nursery stock against San Jose scale 79 

Fungi, saprophytic, accidental occurrence on San Jose scale. 71 

Fungicide, lime-sulfur wash 8 

Fungous and other diseases of San Jose scale 69-71 

diseases destructive to armored scales in Tropics 34, 69 

Fungus. (See Entomosporium maculatum, Micropera cotoneastri, Sphserostilbe 

coccophila, and Spinctrina cerasi. ) 
Fungus, sooty. (See Fumago salicina-.) 

Gleditschia triacanthos, food plant of San Jose scale 39 

Globe flower. (See Kerria japonica. ) 
Gooseberry. (See Ribes oxyacanthoides.) 
Grapes. (See Vitis sp.) 
Hawthorn. (See Crataegus sp. and C. oxyacantha.) 

Hibiscus syriacus, food plant of San Jose scale 39 

Hicoria pecan, food plant of San Jose scale 39 

Honeysuckle. (See Lonicera sp. ) 
Hop tree. (See Ptelea trifoliata. ) 
Horse-chestnut. (See JEsculus hippocastanum.) 
Hydrocyanic-acid gas. (See Fumigation.) 

Insect legislation _ 80 

Insecticides against San Jose scale 72-79 

Insects spreading San Jose scale 57 

Juglans nigra, food plant of San Jose scale 39 

regia, food plant of San Jose scale 39 

sieboldiana, food plant of San Jose scale 37 

Juneberry. (See Amelanchier canadensis. ) 

Kalmia latifolia, food plant of San Jose scale 39 



84 INDEX. 

Kerosene emulsion. (See Petroleum-soap emulsions. ) Page, 

remedy for San Jose scale 76 

Kero-water. (See Oil- water. ) 

Kerria japonica, food plant of San Jose scale 39 

Ladybird, Asiatic. (See also Chilocorus similis. ) 

enemy of Diaspis pentagona 68 

San Jose scale 65-69 

twice-stabbed. (See Chilocorus biculnerus.) 

Ladybirds, Australian, unsuccessful importation into New Jersey 62 

Laurel, mountain. (See Kalmia latifolia. ) 

Legislation against San Jose scale 80 

Lemon. (See Citrus fruits. )• 

Lepidosaphes gloverii, parasitized by Aphelinus fuscipennis 59 

ulmi. ( See also Scale, oyster-shell. ) 

parasitized by Aphelinus mytilaspidis 59 

Ligustrum ovalifolium, food plant of San Jose scale 39 

vulgare, food plant of San Jose scale 37, 41 

Lilac. ( See Syringa vulgaris and S. persica. ) 

Lime-sulfur wash detrimental to establishment of Asiatic ladybird 67 

remedy for San Jose scale 73-75 

value as fungicide - . 8 

Linden. (See Tilia sp. and T. americana. ) 
Locust. ( See Robinia sp. ) 

honey. (See Gleditschia triacanthos.) 

Lonicera sp. , food plant of San Jose scale 39 

Maple. (See Acer sp., A. platanoides, and A. saccharinum.) 

Micropera cotoneastri, accidental occurrence on San Jose scale 71 

Microweisea misella, enemy of San Jose scale 62, 63-64 

spreading San Jose scale 57 

[Pseudoweiseci] suturalis, enemy of San Jose scale 64 

Monomorium minutum, spreading San Jose scale 57 

Morus sp. , food plant of San Jose scale .". 39 

Mountain ash. (See Sorbus sp., S. americana, and S. aucuparia.) 
Mulberry. (See Morus sp.) 

Oil water, remedy for San Jose scale . 77-78 

Orange. (See cdso Citrus fruits and Citrus aurantium.) 

hybrid of trifoliate with sweet, infestation by San Jose scale 42 

mandarin or tangerine type, infestation by San Jose scale 43 

trifoliate. (See Citrus trifoliata.) 

Orcus australasise, enemy of San Jose scale 62 

chalybeus, enemy of San Jose scale . 62 

Osage orange. (See Toxylon pomiferum.) 
Peach. (See Primus persica. ) 

Chinese flowering, food plant of San Jose scale 14 

Pear. (See also Pyrus communis.) 

Kieffer. (See also Pyrus sinensis.) 

immune to San Jose scale -. 42 

Leconte, immune to San Jose scale . - 42 

orchards, in Japan 11-12 

sand, including Kieffer. (See Pyrus sinensis, and Pear, Kieffer. ) 
Pecan nut. (See Hicoria pecan.) 

Pentilia misella— Microweisea misella 57 

Pernicious scale. (See Scale, San Jose, and Aspidiotus perniciosus.) 
Persimmon. (See Diospyros virginiana.) 



INDEX. 85 

Page. 

Petroleum, crude, remedy for San Jose scale 77 

soap emulsions, remedies for San Jose scale 78-79 

Phaitenia glauca, food plant of Aspidiotus perniciosus var. andromelas 55 

Photinia vittosa, food plant of San Jose scale 39 

Physcus varicomis, is it parasite of San Jose scale? 58, 60 

scale hosts 60 

Physocarpus opulifolius, food plant of San Jose scale 39 

Picea alba, food plant oijSan Jose scale. . . _ _ 39 

Plum. ( See Primus maritima, P. domestica, P. triflora, P. cerasifera var. atro- 
purpurea, and P. hortulana. ) 
Poplar. (See Populus sp., P. deltoides, and P. nigra var. italica.) 

Populus deltoides, food plant of San Jose scale 37 

nigra var. italica, food plant of San Jose scale 37 

sp. , food plant of San Jose scale 37 

Privet. (See Ligustrum vulgare and L. ovalifolium. ) 

Prosp>alta aurantii, parasite of San Jose scale „ 58, 60 

Protective resemblance, in San Jose scale 57 

Prunus amygdalus, food plant of San Jose scale - 37 

armeniaca, food plant of San Jose scale 37 

avium, food plant of San Jose scale 37 

cerasifera var. atropurpurea, food plant of San Jose scale 37 

cerasus, food plant of San Jose scale ' 39, 41 

domestica, food plant of San Jose scale 37 

hortulana, food plant of San Jose scale . 37 

japonica, food plant of Jan Jose scale . . 37 

maritima, food plant of San Jose scale . 37 

persica, food plant of San Jose scale 37 

pissardi. (See Prunus cerasifera var. atropurpurea.) 

pumila, food plant of San Jose scale 37 

var besseyi, food plant of San Jose scale 37 

serotina, food plant of San Jose scale 37 

triflora, food plant of San Jose scale 37 

virginiana, food plant of San Jose scale 37 

Pseudoiveisea suturalis=Microiveisea suturalis 64 

Ptelea trifoliata, food plant of San Jose scale 37, 41 

Pyrus baccata, food plant of San Jose scale 37 

communis. (See also Pear.) 

food plant of San Jose scale 37 

malus. (See also Apple. ) 

food plant of San Jose scale 37 

sinensis. ( See also Pear, Kieff er. ) 

food plant of San Jose scale 37 

sp. , food plant of San Jose scale 37 

Quince. (See Cydonia vulgaris and C. japonica.) 
Raspberry, red. (See Rubus strigosus.) 

Rhizobius debilis, enemy of San Jose scale ......... 62 

lophanthse, enemy of San Jose scale 62 

Rhodotypos kerrioides, food plant of San Jose scale 39 

Rhopoideus citrinus, parasite of San Jose scale 58, 61-62 

Rlius cotiniis, food plant of San Jose scale 39 

sp. , food plant of San Jose scale 39 

Ribes aureum, food plant of San Jose scale 37 

nigrum, food plant of San Jose scale 37 



86 INDEX. 

Page. 

Ribes oxyacanthoides, food plant of San Jose scale 37 

rubrum, food plant of San Jose scale 37 

Robinia sp. , food plant of San Jose scale . . 39 

Rosa Carolina, food plant of San Jose scale 37 

lucida, food plant of San Jose scale 37 

rugosa, food plant of San Jose scale 38, 42 

sp., food plant of San Jose scale . 37 

virginiana, food plant of San Jose scale. . 38 

Rose, Japanese. (See Kerria japonica.) 
Riibus canadensis. (See Rubus villosus.) 

nigrobaccus (R. villosus), food plant of San Jose scale 39 

strigosus, food plant of San Jose scale 39 

villosus ( R. canadensis) , food plant of San Jose scale 39 

Salix babylonica, food plant of San Jose scale . . 38 

humilis, food plant of San Jose scale 38 

incana, food plant of San Jose scale 38 

lucida, food plant of San Jose scale -. 38 

pentandra, food plant of San Jose scale - , 38 

sp. , food plant of San Jose scale - 38 

vitellina, food plant of San Jose scale 38 

Sambucus sp. , food plant of San Jose scale. 39 

San Jose scale. (See Scale, San Jose.) 
Sassafras. (See Sassafras officinale.) 

officinale, food plant of San Jose scale 39 

Scale, Chinese. (See Scale, San Jose, and Aspidiotus pemiciosus.) 

insects, various methods of reproduction 43-44 

oyster-shell. (See also Lep>idosaphes uhni. ) 

probably parasitized by Anaphes gracilis 60 

pernicious. (See Scale, San Jose, and Aspidiotus pemiciosus.) 
San Jose. (See also Aspidiotus pemiciosus.) 

activity of young larva 43, 45, 51, 57 

adult female, description . : 54 

male, description 53 

and citrus fruits 42-43 

climate as affecting spread 33-34 

color protection 57 

control 72-79 

damage, nature 34-36 

descriptions of scale and insect 51-54 

destructiveness 7 

distribution and present condition, by States and Territo- 
ries 18-33 

by faunal zones 33-34 

means 56-58 

egg, description 51-52 

explorations in eastern Asia to determine origin. . ... 11-15 

fecundity 48-51 

female, third stage, description 53 

first establishment in the United States 10 

food plants 36-43 

fungous and other diseases 34, 69-71 

generations 48-50 

habits and life history 34-55 

hibernation _ 43, 50 



INDEX. 87 

Page. 

Scale, San Jose, history in California and the West 15 

East 16-17 

immunity of Leconte and Kieff er pears 42 

in Alabama 20 

Arizona 20 

Arkansas 20 

Australia 10 

California 20-21 

Canada 33 

Chile 10 

China 13-15 

Colorado 21 

Connecticut "21 

Delaware 21 

District of Columbia 22 

Florida 22 

Georgia i 22 

Hawaiian Islands 10 

Waho 22-23 

Illinois 23 

Indiana _ 23 

Iowa 23 

Japan - n-13 

Kansas 24 

Kentucky 24 

Louisiana 24 

Maine 94 

Maryland 25 

Massachusetts 25 

Michigan _ _ 25-26 

Minnesota 26 

Mississippi . 26 

Missouri 26 

Montana . 26 

Nebraska 26 

New Hampshire 26-27 

New Jersey 27 

Nevada 27 

New Mexico 27 

New York 27-28 

North Carolina 28 

North Dakota 28 

Ohio 28 

Oklahoma 29 

Oregon 29 

Pennsylvania 29-30 

Rhode Island ; 30 

South Carolina • 30 

South Dakota 30 

Tennessee ." 30-31 

Texas 31 

Utah ' 31 

Vermont 31 

• Virginia 31_32 



88 INDEX. 



Scale, San Jose, in Washington - 32 

Wisconsin . 32 

West Virginia 32-33 

Wyoming 32 

indirect benefits 9 

insect enemies, status 9, 58-69 

insecticides 72-79 

introduction into United States, supposed manner 15 

issuance of adult males 47 

larva, second stage, description 52 

newly hatched, description 52 

legislation 80 

life history 43-51 

on Chinese apples, haw apples, and pears 14 

origin - 10-15 

parasites 58-62 

plants commonly or badly infested 36-38 

not infested 40-41" 

occasionally or rarely infested 38-39 

predaceous insect enemies 62-69 

present status of problem 8-10 

propupa of male, description 52-53 

pupa of male, description 53 

record of spread in United States. 15-34 

relationships - 54-55 

remedies - 72-79 

reproduction 43-45, 50-51 

resemblance to Entomosporium maculatum 35 

scale covering, how formed 45 

of female, description 51 

male, description 51 

seasonal history . 43-50 

sources of infestation in East 17-18 

States still supposedly uninfested 19-20 

systematic position 54-55 

viviparous habit 43-45 

white peach. (See Diaspis pentagona.) 

Scales, armored, subject to fungous diseases in Tropics 34, 69 

Shad-bush. (See Amelanchier canadensis.) 

Smoke bush. (See Rhus cotinus.) 

Snowberry. (See Symphoricarpos racemosus.) 

Soap, whale-oil or fish-oil, remedy for San Jose scale 75-76 

Sorbaria sorbifolia (Spirasa sorbifolia), food plant of San Jose scale 39 

Sorbus americana, food plant of San Jose scale 38 

aucuparia, food plant of San Jose scale 38 

melanocarpa, food plant of San Jose scale ^ . . 38 

sp., food plant of San Jose scale 38 

Sphserostilbe coccophila, fungous enemy of San Jose scale 34, 69-71 

Spinctrina cerasi, accidental occurrence on San Jose scale 71 

Spiraea sorbifolia. (See Sorbaria sorbifolia.) 

sp., food plant of San Jose scale 39 

Spruce, white. (See Picea alba.) 

Sumac. (See Rlius sp.) 

Symphoricarpos racemosus, food plant of San Jose scale — ' — 38 



INDEX. 89 

Page. 

Syringa persica, food plant of San Jose scale 38 

vulgaris, food plant of San Jose scale 38 

Thorn s silver. (See Elseagnus longipes.) 

Thuya occidental-is, food plant of San Jose scale 39 

Tilia americana, food plant of San Jose scale 38 

sp. , food plant of San Jose scale . 38 

Toxylon pomiferum, food plant of San Jose scale 38 

Typophorus canellus, spreading San Jose scale 57 

Ulmus americana, food plant of San Jose scale 38 

campestris, food plant of San Jose scale 38 

sp., food plant of San Jose scale 38 

Verrnorel nozzle, for spraying lime-sulfur wash 75 

Viburnum cassinoides, food plant of San Jose scale 39 

opulus, food plant of San Jose scale 39 

sp. , food plant of San Jose scale 39 

Virginia creeper. (See Ampelopsis quinquefolia.) 

Vitis sp. , food plants of San Jose scale 39 

Viviparous habit of San Jose scale 43-45 

Walnut. (See Juglans nigra, J. regia, and /. sieboldiana. ) 
Willow. (See Salix sp., S. pentandra, and S. babylonica.) 

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